Solving a quadratic by completing the square

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👉 Learn how to solve quadratic equations by completing the square. When solving a quadratic equation by completing the square, we first take the constant term to the other side of the equation and create a perfect square trinomial with the quadratic term and the linear term. If the coefficient of the quadratic term is not 1, we factor out the coefficient before creating the perfect square trinomial.
The perfect square trinomial is created by adding to both side of the equation, the square of half the coefficient of the linear term (the term whose variable is not squared). Note that you must account for the factored out value when adding the square of half the linear term to the other side of the equation. Then the perfect square trinomial is evaluated and then we solve for the variable to get the solution(s) to the quadratic equation.
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Organized Videos:
✅How to Solve a Quadratic by Completing the Square
• How to Solve a Quadrat...
✅Solve a Quadratic by Completing the Square | Fractions
• Solve a Quadratic by C...
✅Solve a Quadratic by Completing the Square | -x^2+bx+c
• Solve a Quadratic by C...
✅Solve a Quadratic by Completing the Square | 2x^2+bx+c
• Solve a Quadratic by C...
✅Solve a Quadratic by Completing the Square | ax^2+bx+c
• Solve a Quadratic by C...
✅Solve a Quadratic by Completing the Square | x^2+bx+c
• Solve a Quadratic by C...
✅Solve a Quadratic by Completing the Square | Learn About
• Solve a Quadratic by C...
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#Solvequadratics #completethesquare #brianmclogan

Опубликовано:

2 дек 2012

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Комментарии : 1,7 тыс.

@brianmclogan 4 месяца назад

Quick Guide to Completing the Square - ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-MveZ6dyKMuA.html

@LUCIFERxJN 27 дней назад

One thing I would do differently is I would do a times c which would be much easier to solve

@MFM230 3 года назад

I was impressed by the teacher, Mr. McLogan, who kept stopping to answer a question from a student. I bet he is a great teacher. Also, too many math teachers skip steps because the skipped step is "obvious." Of course, it it obvious to highly intelligent people with a gift for math. Mr. McLogan did all the steps. Very well done!

@Abc-xm8pb 2 года назад

THISS!!! They always skip explanations

@Idkwhatnametouse169 2 года назад

@@Abc-xm8pb Right- like they combine 3 steps like its normal. Im in a new district and in a grade above what I’m supposed to be in (so I didn’t learn what they did/what they did) and its so annoying because I get lost so fast. Then my parents get mad at ME for not paying attention in class when I am and asking questions but shes so hard to approach-

@FrankCordovaMileHighBorn 2 года назад

Oh yeah, shows he has the patience to work the problem step by step.

@casparstanford382 Год назад

Thing is tho since iam used to teacher skipping obvious steps when they actually go through the obvious steps i get more confused than if they dont go through obvious step

@bigfatpoo8104 Год назад

Theres no such thing as someone who is gifted at something they need to learn

@nathanshell1846 Год назад

Not the hero we deserved, but the hero we needed. This man is carrying me through my college courses. Thank you Mr. Brian McLogan. I owe you bigtime!

@asaurdreams1850 Год назад

batman revealed????

@brownb154 10 месяцев назад

Not the hero we deserved, but the hero we needed. This man is carrying me through my college courses. Thank you Mr. Brian McLogan. I owe you bigtime!

@AceWantsYourMilk 2 месяца назад

It makes me proud to know I can understand a little bit of college material when I’m only in middle school 😅

@brianmclogan Год назад

Updated Explanation - ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-JtUq2PojEWg.html Download the Guide (PDF) - www.brianmclogan.com/SolvebyCompletingthesquarepdf Purchase the Answers (PDF) - brian-mclogan.creator-spring.com/listing/solve-by-completing-the-square

@adityamadiraja1235 6 лет назад

I got a 100% in 3 of my most important tests because of you! Thank you and keep making more videos like this!

@brianmclogan 6 лет назад

Awesome Aditya! happy to be there for you

@mikeoliver5671 2 года назад

There are 3 methods: 1) factorise, if possible (by far the easiest, when possible). If not 1), then 2) use the formula for roots of a quadratic equation (x = -b +/- etc) 3) complete the square, which is preferred when the coefficient of x is an even number. {Completing the square in such a case also reveals the co-ordinates of the Vertex eg with y = x^2 -4x -2 , completing the square yields y = (x -2)^2 - 6 which has a minimum value of -6 when x = 2. The Vertex is the point (2, -6)}, which also reveals the Axis of symmetry ie the line x = 2. A useful "test", so to speak, is to get students to work out the discriminant (b^2 - 4ac) which always tells the student a lot about the quadratic. Evaluating the discriminant is never a waste of time, because --- it's good mental gymnastics ie brain exercise, with the additional caveat of the dangers of negative numbers, and --- prepares the student for the type (and graph) of the quadratic they are dealing with. eg when b^2 - 4ac = 0, there is only one real root, which means the quadratic itself is a perfect square. Useful for predicting solutions and sketching graphs. In the case above, b^2 - 4ac = 81, which number is a perfect square. When the discriminant is a perfect square, the quadratic has 2 real roots, which means that it can be factorised. ALWAYS. 2x^ + 7x -4 = 0 ==> (2x - 1)(x + 4) = 0. x = 1/2 and x = -4. The question itself confuses me, so with respect: Mr. McLogan, why would you get students to complete the square on 2x^2 + 7x -4 =0, unless it was specifically to teach/reinforce the technique of completing the square itself? Completing the square on a Quadratic that can be factorised is unnecessarily complex and takes more time than factorising. Flexibility is key and in Exams/Tests, a time-saver.

@thankyouuuuu2039 29 дней назад

thank man

@thankyouuuuu2039 29 дней назад

thanks man

@DimphoTsaModimo 2 года назад

This video was recorded in 2012 but it still helped me a lot even in 2021 at varsity...Thank you so much, Sir. May God bless you.

@RhythmicSoundwaves Год назад

In high school I decided not to pay attention in school, starting hanging around the wrong people and eventually after high school got my life in check and decided to go to college. I struggled so hard in math because of my HS situation. Your videos have helped so much. Today I can say I've graduated with a B.S in Exercise Science and on my way to getting a Doctorate.

@brianmclogan Год назад

Love it, congrats to you

@toahnailor Год назад

@@brianmclogan it’s really cool that you are still replying to comments even after 10 years

@JaCrispy313 2 месяца назад

Just curious, are you in PT school? Lol I’m thinking of doing exercise science, how was it?

@copkhan007 4 года назад

Math is the reason i became a Chef. Just cut, chop, cook and present. EASY.

@steviepigford8485 4 года назад

LMFAO 😁 😂❤️💚 💛 hahahaha

@1polyron1 4 года назад

well when you put it like that... but I'm sure being a chef is a little more nuanced than that buddy ;)

@turtletube 3 года назад

@twistedblktrekie you win this time

@strawberrys4440 3 года назад

@@turtletube I- did someone post that on your comment. FYI don’t let ppl get to u lol. Nobody asked and? Who cares it’s the internet ppl can comment what the fuck they want

@danielamaning5765 3 года назад

Funny

@jenniferpacheco2569 4 года назад

stop looking at comments and study 😂

@suvangoda7773 4 года назад

lol... this is hard :(

@sanjanagautam3583 4 года назад

Very funny

@vasanthavasuu1874 4 года назад

@woni9834 4 года назад

Jennifer Pacheco read my comments because the teacher is not teaching you the right way. It took him 3 minutes to solve a 30 seconds question!

@blockydogy1188 3 года назад

hahahaha this is very funny

@thembekilendlangamandla516 6 лет назад

I wish I was part of the class being taught 😭😭❤

@brianmclogan 6 лет назад

well you have the next best thing I guess, the recorded version

@mathewthomas6694 8 месяцев назад

10 years later and this video still helps people like me - thank you for being a great teacher Mr.Logan

@johncrofford 3 года назад

As someone who gets to explain this several times a year, I appreciate you taking the time to do this in front of a camera. Not sure why you didn't simplify that 2 out like you wanted to at the beginning, though. Simplifying as much as possible as early as possible cuts down on sloppy errors later.

@amadain17 3 года назад

I was literally screaming that at the video from the start. He made this overly complicated.

@mattslupek7988 2 года назад

I know. While he was doing all that, I had already solved the equation in my head using the quadratic formula, thus getting {2, -4} as my answer.

@LordVoltRod2c 2 года назад

The fact he did not simplify offered a refresher course though. Now I don't have to go and learn fractions operations all over again. In structural design fractions are very common and you have to get used to them. 😑 Can't just ignore them as that would prove fatal. For me the video was a blessing.

@ML-hs3ld Год назад

@Matt Slupek 1/2, not 2.

@daraung3175 6 лет назад

After finish giving a lecture on solving a quadratic equation. Teacher: Any question? Student raises hand. Student: So a lot of it is algebra stuff.

@brianmclogan 6 лет назад

haha yes

@thenudebrewer7466 4 года назад

Solve almost any calculus problem in 10 steps and it's almost always: 5 steps of algebra, 1 step of calculus magic, 4 more steps of algebra. Mastery of Algebra is so incredibly fundamental to all higher math.

@Supernaut70 4 года назад

and basic operations such addition and subtraction

@TDSONLINEMATHS 4 года назад

very nice, you can also check out on my channel for more mathematics contents

@glennwadlegih1896 2 года назад

I’ve been out of school for a very long time and have had a successful career in medical device engineering. I’ve honestly forgotten how good it was to have a great math teacher. I was fortunate to have quite a few of them and you are one of the good ones. When you are having a though day, remember you are making a difference!

@EmpyreanLightASMR Год назад

College calc student here. You'll be doing this stuff all over again lmao here I am trying to refresh. Brings back memories of high school haha

@brianmclogan Год назад

Lots of repetition👏👏👏

@maxvetotobis 5 лет назад

This has me so lost man.

@IO23777 3 года назад

There are easier methods for solving a quadratic - Besides he may have been showing this particular example to students for years

@chokrimzoughi3330 3 года назад

He makes it very complicated but it’s very easy if you use the formula delta = b square-4 ac ..a=2 , b=7 and c = - 4 .. so delta = b square - 4 AC = 49 -( 4 times 2 times -4 = 81 .. then x1 = (- b - square root of delta )all divided by 2A .... square of delta = square root of 81 =9 .. x1 = (- 7 - 9 ) divided by 4 =-16 /4 =- 4 ..X2 = (-B + square root of delta ) /2A = (-7 + 9 ) / 4 = 2/4 = 1/2 ..

@rassular 3 года назад

@@chokrimzoughi3330 sorry I don't speak Brazilian Portuguese.

@rpap5322 3 года назад

i pretty much think that is this mans theory.....

@michaelszczys8316 3 года назад

I can’t do this kind of math AT ALL. That’s why I’m a welder and not an engineer.

@migelchavez7007 Год назад

Thanks you, you made me understand this material way better than my teacher .

$@hodayaifrach9637$

@hodayaifrach9637 Год назад

yup, same for me

@sharonroy6884 6 лет назад

Thank you this is really helpful! It would be great if you could upload some problem solving questions that include completing the square or parabolas in general. Thanks

@brianmclogan 6 лет назад

I just made some videos on that, will be uploaded within the next week. If you need some examples now, here is just one of my playlists with completing the square ru-vid.com/group/PL0G-Nd0V5ZMq-1D6604jY8aFUjYuk4Kkh

@tweeterthemonkeyman383 6 лет назад

This is why i cheated in HS.

@brianmclogan 6 лет назад

haha okay

@lorenzovonmatterhorn4756 6 лет назад

you're pathetic if you can't do simple algebra. Congrats with your future as a cashier lmao

@blackoutemzz2674 6 лет назад

It's so easy I solved it less than 2 minutes

@Davehash 6 лет назад

+Kevin Contreras Hey! Squidward is doing great as a cashier.

@talhajat3301 6 лет назад

I'm doing great as a business man, trust me, you won't be using this math after high school

@utyouba 7 лет назад

Hi Brian. Many thanks for this ! Just one thing puzzled me ... when you had 2(x^2+7/2x)=4 why didn't you divide both sides by 2 to leave x^2+7/2x=2 ? This would give easier numbers to work with later on.

@brianmclogan 7 лет назад

not sure, great idea will look into trying it next time

@mrkarimmath 7 лет назад

what's your opinion in my video ? pls write to me

@justinlin3258 7 лет назад

You could have done it this way. But when finding the vertex form it is much more similar to what the guy in the video has done.

@Eaglesda21 7 лет назад

[I believe] it all depends on the reason you are completing the square. If your goal is to solve (find the value(s) of x that satisfy the equation) 2x^2+7x-4 = 0 then dividing by 2 will not change your final solution (as long as you divide both sides by 2). However, if your goal is to eventually graph the function, you will change its shape if you divide by 2. I believe this is why most textbooks (and teachers) default to the type of procedure shown in this video; to prevent you from changing the shape of the graph.

@chinareds54 6 лет назад

Multiplying or dividing both sides of an equation does not change the graph. y=x looks exactly like y/2 = x/2. And he does divide both sides by 2, he just does it on step 8 instead of step 2.

@paultucker8386 7 лет назад

MUCH EASIER TO DIVIDE EVERTHING BY 2 AT THE BEGINNING!

@brianmclogan 7 лет назад

except 7 is not divisible by 2

@1up910 6 лет назад

ibrahim kuyumcu is that a whole number?

@davidnethery9732 6 лет назад

Tomato, Tomahto

@pikapoo762 5 лет назад

so u just get 7/2. i didit that way and got the same answer without confusing myself.

@milenelopes13 5 лет назад

@@brianmclogan Divide it and leave it as a decimal. 3.5

@RyansTechReviews29 Год назад

Thanks, I've been really struggling on completing the square and solving quadratic equations overall. Your video helped clarify step by step in the littlest detail. Once again, thanks man.

@chrisjenkins5887 5 лет назад

Why is this 500 times more efficient than what I was shown in class? I thank you monumentally for this.

@patrickjoyce244 4 года назад

this man is every race in one

@buddydog1956 4 года назад

wasn't ready for that one!!! LOL!!!

@brianphillips5576 4 года назад

You have the patience of a saint. It's good to see a gifted teacher teach.

@CharlieTechie 4 года назад

If you are having problems with solving a quadratic by completing the square, check out: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-6Py8L708OUA.html He presents a much simpler and clearer teaching style.

@rhiannalopez3805 2 года назад

you remind me so much of my teacher I had my junior year of high school! I loved his teaching methods and he did so well explaining concepts. He was my favorite and I hated math but he made it so much more fun and worth sitting through a 50 min lecture.

@understandingmaths1033 6 лет назад

Just to point out, you don't have to eliminate the x^2 coefficient. You could double instead to make 4x^2 + 14x = 8. Then to make a perfect square on the LHS: 4x^2 + 14x + 49/4 = 8 + 49/4, etc. A grid method is helpful to see how this works.

@brianmclogan 6 лет назад

that is correct

@t-rex2466 Год назад

Wow your smart too

@dumbelldorkx2568 7 месяцев назад

Such an amazing instructor. for someone scared of fractions, professor mclogan made me understand it so easily

@joanlynch5271 5 лет назад

Thanks Mr Brian McMathman!

@midwestrailroadproductions8116 5 лет назад

Hey, Brian. Completing the square is a good method for calculating the roots of a quadratic equation. It works when there is no leading coefficient and the b term is even, even though the quadratic formula would give the correct solution each time. I know about mixed numbers and improper fractions. I was stuck with that in Mr. Caslow's class, but now I feel more confident.

@brianmclogan 5 лет назад

agree! happy to help

@ewew9684 4 года назад

i love how he acts that he has students in the room or is he?

@Ass-uq3sz 4 года назад

I think he just records his actual classes

@1polyron1 4 года назад

are you okay?

@reizer05 4 года назад

Actually he has.

@heystobit9194 5 лет назад

i’m in year10 and i’ve just come across learning something like this. it’s the first time I know that maths is going to take a turn. and your video helped explain everything !! thank you! :)

@brianmclogan 5 лет назад

Cheers, Keep working hard

@JeonJungkook-vv3qd 4 года назад

Hi Army Stream ON

@josephkamundi378 4 года назад

Wow

@josephkamundi378 4 года назад

PRACTICE MAKES PERFECT. AND NOBODY IS PERFECT, SO WHAT IS THE POINT OF PRACTICING?

@aspenrebel 3 года назад

You are either in England, Oz, or NZ. "maths". "year 10".

@Less1leg2 4 года назад

glad he walked all the steps through and described where what came from to get to.

@ahazzamayoub9218 4 года назад

you just need to factorise the equation and you get the same result only in two lines thanks soo much

@kamikazeyamamoto4545 6 лет назад

I am in class and already lost so I raise my hand. Brian McLogan (Teacher): "Yes, Kamikaze you have a question?" Kamikaze (Me): "Yessir, just one." Brian McLogan: "What is your question?" Me: "Can I transfer out of this class and sign up for Shop instead?"

@brianmclogan 6 лет назад

"sure" haha

@ajfdjhb Год назад

Thank you! I'm a 7th grader being forced to take algebra lessons that are really hard to understand. With your video, you really helped me a lot and I appreciate it. Keep up the good work!

@SierNotsruht Год назад

How is algebra hard to understand, I'm also a 7th grader and I know calculus 1

@goldenfox2385 11 месяцев назад

@@SierNotsruhtsure kid💀

@chiehlt2181 10 месяцев назад

@@SierNotsruht ur profile pic clearly reflects u. not everyone is as "smart" as u. also who asked idiot?

@Danksigmalord 10 месяцев назад

@@SierNotsruht your a 7th graders with a nerd profile picture, just gonna guess that when you say you "know" calculus 1, you just mean you've seen a 10 minute video about it on RU-vid and consider that enough to act like an expert.

@silas6740 9 месяцев назад

your pfp says it all nigga @@SierNotsruht

@-optional-9189 6 лет назад

This video was very helpful! Thank you so much for making this!

@brianmclogan 6 лет назад

you are very welcome!

@LordVoltRod2c 2 года назад

Thank You to the teacher and the class input. This video was packed full of useful information!

@brianmclogan 2 года назад

Awesome so happy to help!

@alexboughlef9280 6 лет назад

This vid helped a lot, I don't think I ever knew how to complete the square when the coefficient of a quadratic equation was greater than 1

@brianmclogan 6 лет назад

great! now you know!

@connermacfarlane1036 5 лет назад

You can just use the quadratic formula

@connermacfarlane1036 5 лет назад

@@brianmclogan great videos

@SeeTv. 4 года назад

8:01 It makes me crazy that he didn't write an equal sign at this point. xD

@boots11234 8 месяцев назад

Thanks for the help. My son was struggling with this. I’ve had 2 years of calculus 20 years ago but needed to dust off the cobwebs. Watched your video, showed my son how to do them. Got to bond with and teach my son at the same time. Thank you for this ❤

@yvonneandbillmarshall2724 3 года назад

Good classroom control while explaining a tough problem! Kudos!!!

@AlexisNagler 3 года назад

watching this in preparation for a test I"ve got to take over zoom tomorrow. Made me so sad :/ kinda miss being in a real classroom

@danielc379 3 года назад

same

@puddingg7861 3 года назад

how was the test?

@vidushhhhii 3 года назад

OMG that's the exact same reason I'm here today 😭

@herbcruz4697 5 лет назад

I'm just wondering. Wouldn't it have been easier/faster, after factoring out the 2, to divide both sides by 2, at that point?

@bowlchamps37 4 года назад

Divide by 2 and then use the p-q-formula or Quadratic formula

@aspenrebel 3 года назад

NO! Cuz then on the right side you are doing "0/2" which is a NO-NO!! Rights side still 0, but you've changed the left side. It will mess everything all up, and screw you up.

@aspenrebel 3 года назад

Or are you talking about AFTER he adds 4 to both sides?

@herbcruz4697 3 года назад

@@aspenrebel 0/2=0. You're not dividing by zero. In other words, 2x^2+7x-4=0 2(x^2+(7/2)*x-2)=0 x^2+(7/2)*x-2=0 x^2+(7/2)*x=2 At this point, we have already gotten a coefficient of 1 on the x^2-term, and then moved the constant term to the other side of the equation, so now, we can go down the route, where we complete the square.

@aspenrebel 3 года назад

@@herbcruz4697 ok, I guess I was thinking dividing both sides by "x", would give right side of 0/x. Nevermind.

@jamming0069 6 лет назад

07:02 that sudden change of expression, yet I love how you teach. please keep it up! I'm having a hard time with my calculus, I find this channel to be very very helpful for the journey.

@brianmclogan 6 лет назад

happy to be there to help you Erloel!

@aspenrebel 3 года назад

Oh! change of expression IN HIS FACE!! I thought you were saying he changed the expression in the equation at 7:02. I was like "what?".

@joyjika9819 4 года назад

Teacher: Any questions? Students: *coughs* Teacher: You guys are acting like I just killed you. 😁

@turtletube 3 года назад

see this is why i really dislike math he filled up the whole board for one problem one freaking problem!!!!

@ccsddhdnc8548 3 года назад

Lame no one cares

@turtletube 3 года назад

@@ccsddhdnc8548 your right bro whyd i even write this comment

@ngndnd 3 года назад

he made this more complicated than it needed to be tho

@strawberrys4440 3 года назад

@@ccsddhdnc8548 smh ❄️

@chocolateangel8743 3 года назад

Math is the language of numbers. If you want to be good at it, you first have to know how you, as an individual, learn it. I, for example, don't learn math in the same way I do other subjects. I actually had to research different learning styles and try them out -- until I found what worked for me (visual and conceptual math learner). Basically, I need to understand the mathematical logic and concepts behind what I'm doing in order to grasp algorithms. I will take a long problem, break it down to its core concepts and study each of them -- until I've mastered them. I also learn faster from video (taps into multiple senses at the same time) than I do books. Even though video helps me to learn faster, I will still take notes (also helps me to learn/remember things). After I have watch videos on the core concepts (typically twice each) and have taken notes, I will attempt to do problems on my on -- starting with simpler ones and working up to hard ones. If I notice that I keep messing up in a certain spot, this lets me know I need to review a concept. I do this until I feel comfortable -- and until I can fully explain things to myself. This includes the concepts, logic, and various approaches. Looking up various approaches (and videos by different people) can help you to gain a deeper perspective. I've found that no one instructor answers all of my questions.

@qazji283 6 лет назад

Hi, thanks for this video really helped! I was just wondering how you could find the turning point from this?

@brianmclogan 6 лет назад

you would need to find the vertex. when you convert the equation to vertex form the vertex is (h,k) I have plenty of videos on finding the vertex by completing the square

@qazji283 6 лет назад

ok thanks will have a look

@mikeoliver5671 2 года назад

"how you could find the turning point from this?" 1) Easiest when the coefficient of x is an even number eg (from my reply above): eg with y = x^2 -4x -2 , completing the square yields y = (x -2)^2 - 6 . Now look at the (x - 2)^2 , which has a minimum value of 0, when x = 2. So the quadratic has a minimum value of -6 when x = 2. The Vertex is the point (2, -6), which also reveals the Axis of symmetry ie the line x = 2. OR 2) From y = ax2 + bx + c, calculate -b / 2a. This is the x-coordinate of the vertex. To find the y-coordinate of the vertex, substitute the value of x = -b / 2a into the equation for x and solve for y. OR 3) Find dy/dx, which = 0 at the turning point (Vertex) From y = x^2 - 4x - 2 dy/dx = 2x - 4 which = 0 when x = 2 (substitute back into y, and y = -6) Which method you'll use will beceome clearer to you with practice.

@Chanakya50BC 4 года назад

Those who find this difficult, are advised to use the trinomial method. Refer: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-T2F0qF1QlYE.html

@flyaway8780 2 года назад

thank you! this helped me nearly 10 years later, somehow i didn't get this in class but i understood it so easily with your teaching.

@drfoxcourt 4 года назад

Missed the important step of checking that your answer actually works.

@aspenrebel 3 года назад

I did that.

@lissiemackintosh 7 лет назад

This is going to help me so much in tomorrow's exam! Thanks from the UK!

@brianmclogan 7 лет назад

cheers! good luck

@aashitAgrawal 6 лет назад

Thank you so much man! You are genius, I understood it very well. Thanks! ♥

@brianmclogan 6 лет назад

awesome! happy to help

@FrankCordovaMileHighBorn 2 года назад

Man this is good stuff. I wish I had someone like you when I was in grade school and college as you showed patience working that problem.

@malikamost3888 6 лет назад

thanks so much,it really helped !!! x

@brianmclogan 6 лет назад

awesome! happy to help

@duanebalch8337 4 года назад

in my head i revert back to a FOIL method and solve each for 0. giving me 1/2 and -4, proofed it and all under 2 minutes. not bad for an older guy that hasn't seen a quadratic for 26 yrs. (actually i'm just glad I had the right answer LOL)

@michelbertrand2652 3 года назад

Beaucoup trop long alors qu avec le discriminant il faut 10 secondes mentalement

@p0k3r 7 лет назад

Sir! i have a question thus the dividing at 7:36 is it depends on what u multiply or on the number outside the paraheis i what your going to divide?

@brianmclogan 7 лет назад

correct, inverse operations

@ericalukitomccharles4523 25 дней назад

"You guys act like I just killed you." 😂

@poonchild 5 лет назад

You're a very good techer.

@brianmclogan 5 лет назад

Thanks

@GTX1050VSNEXTGENGAMES 6 лет назад

randy orton

@Kenji-ug5bo 6 лет назад

Max Payne 3

@user-in1xb8vg7s 6 лет назад

Lmao

@moisescovarrubias3288 3 года назад

Thank you so much! This helped me finish those few quadratic problems that I was freaking out about on a test.

@brianmclogan 3 года назад

Best of luck!

@pratyushkamboj634 6 лет назад

I really needed this for my tution homework. Thanks!!

@brianmclogan 6 лет назад

you are very welcome!

@Obisiks500x 5 лет назад

Thanks so much! For some reason I had no idea that I had to multiply the factored out number with the 'c' variable.

@brianmclogan 5 лет назад

You are very welcome

@sasusan1 4 года назад

Look at the confusion on the board...damn

@queentesna8314 6 лет назад

thnx a lot my mind was hazy previously about solving them but now u just cleared the vagueness

@brianmclogan 6 лет назад

you are very welcome!

@sashier987 2 года назад

I wish this man was my teacher. I love his explanations

@deanneubauer6344 4 года назад

I look at the equation and my brain says (2X - 1)(X + 4)=0. So, the roots are X = 1/2 and X= -4.

@user-bn5bm4ys6j 4 года назад

Me too

@marlinellis4993 3 года назад

Same here. The entire time I’m like I did this in my head in 30 seconds, why such a long video lol.

@dongwenwan2767 3 года назад

me too

@johnnewell3530 3 года назад

I guess he’s teaching a theory for when the result isn’t so deducible. But yes this problem only actually take a 10sec by factoring the equation

@aspenrebel 3 года назад

What if the equation is more complicated, that you cannot really on your education and experience with such equations to be able to figure it out on site. He's showing a method to solve it, which can be used for even more complicated equations.

@kebichlact6677 4 года назад

im taking calc 2 in college and ive never learned to do this jajaja, i always resort to the quadratic formula

@johncrofford 3 года назад

The quadratic formula is this process applied to the standard form of a quadratic.

@macromedia1489 3 года назад

you have helped me so much with my college final, thank you!

@davidr9239 6 лет назад

Great video! Thank you.

@brianmclogan 6 лет назад

you are very welcome!

@savannahngl 3 года назад

So that’s how you do it! Can’t believe I got passed 6th grade, my high school math teacher sent me here lol.

@lionelgunathilake 4 года назад

I saw this video unexpectedly and I was shocked. Those steps are really complicated. I was taught by my teachers to follow very simple steps when I was in grade 8. The steps are given below. 2x2+7x-4=0 2x2+8x-x-4=0 2x(x+4)-1(x+4)=0 (x+4)(2x-1)=0 x+4=0 or 2x-1=0 x=-4 or x=1/2

@sugar3827 4 года назад

ලයනල් ගුණතිලක your method is solving using factorising, not by completing the square. This video is about completing the square.

@leonardmboloma5281 4 года назад

your method is simple n correct but it is not completing the square. You cannot have 2x2 in completing square

@bartonpaullevenson3427 4 года назад

Very clear! Thanks!

@afhamarif3133 Месяц назад

the end part just killed me 💀

@msucds1 5 лет назад

There is an easier way, it called a TI-89.

@ishanchoudhary4179 3 года назад

LOL TEXAS FOR LIFE

@aspenrebel 3 года назад

skip to the end of the video.

@beverlyfrancis8433 4 года назад

You lost me after placing the square. But I learnt a new skill before I got lost.

@shortyxo737 5 лет назад

love your teaching style!

@avan4544 5 лет назад

man this guy honestly is a life saver

@MrGriff305 4 года назад

That was a bit of a mess.. It'd help to improve a bit on cleanliness of presentation. Also, I got the answers quicker through trial and error iterations.

@anymaths 4 года назад

learn maths from my maths videos.

@HandsomeJackoff 5 лет назад

I'm actually in love with this man.

@brianmclogan 5 лет назад

Thanks!

@cool98ish 2 года назад

I LOVE THESE VIDEOS!!!! OMG SO HELPFUL!!! I remember watching these videos when I was doing math in high school in 2015. Now, 7 years later, I'm watching these same videos to refresh my memory and help my brother with his math homework. Oh yeah, he's also in high school now 😳. Time flies!

@nitelik9887 5 лет назад

These videos really help me to learn better. Thank you so much :)

@brianmclogan 5 лет назад

you are very welcome Nitelik!!

@mohammadafaneh8595 5 лет назад

Quadratic formula man

@matthewb-r488 5 лет назад

math isn’t just about memorizing formulas. It’s about understanding why things are true. So tell me, why does the quadratic formula work? How did the first person figure out the quadratic formula?

@dean10956 5 лет назад

subaru connatoo bro were just trying to get through high school man

@herbcruz4697 5 лет назад

He was teaching a section on how to solve quadratic equations by completing the square, and this was his example. Personally, based on the answers, I would have solved this equation by factoring, and granted, the quadratic formula always works, but completing the square is where the quadratic formula comes from.

@mmkamal5842 4 года назад

Brian why did you make things complicated? 2xx+7x-4 = 0 or, 2xx+8x - x-4=0 or, 2x(x+4)-1(x+4)=0 or, (x+4)(2x-1)=0 so it is x=-4 or x=1/2.

@alaincurtin6851 6 лет назад

Thanks Logan

@brianmclogan 6 лет назад

you are very welcome!

@mjcard 4 года назад

At the end,it looked like really cool wall paper.

@faisalsultan3044 7 лет назад

This is the longest possible way of doing this question. There is a sooooo much easier and shorter way. I don't know what it is but american people do it this way. Teachers in England have a method that takes one quarter of this much time. Or it's just that in years higher than me they do it this way. But all I know is that it could be done much quicker.

@brianmclogan 7 лет назад

this is me breaking it down slowly for my students. In my pre-calculus class we go much faster. Not sure if it is the same way you are describing though

@dottyc5232 6 лет назад

TELL ME PLEASSSSEEEEEE

@astaroth7981 6 лет назад

ax^2+bx+c -------> 2x^2+7x-4=0 Δ=b^2-4ac -------> 7^2-4(2*(-4))= 49+32=81 √Δ=√81=9 x=(-b-√Δ)/2a and x=(-b+√Δ)/2a -------> x=(-7-9)/4=-16/4=-4 and x=(-7+9)/4=2/4=1/2

@faisalsultan3044 6 лет назад

Say we have: 2x^2-8x-4=0 1) Factorise and take the coefficient of a out. (Don't factorise the c, the last number) 2(x^2-4x)-4=0 2)Complete the Square of the equation in the bracket. 2[(x-2)^2-4]-4=0 3)Expand, but only the last number in the squared bracket. 2(x-2)^2-8-4=0 4)Simplify and solve. 2(x-2)^2=+12 Divide by 2 (x-2)^2=+6 Root x-2=+or-√6 add 2 x=2+√6 OR x=2-√6 This obviously works for all equations when the coefficient of a is not 1. I used 2x^2-8x-4=0 Because it was easier to write in the comments than the equation in the video.

@rlfrohs 6 лет назад

Brian McLogan no it's awful and confusing. Check out yaymath with Robert ahdoot.

@haroldlake1005 3 года назад

Use the expression: (-b +/- V(b2 -4.a.c) / 2a , and it will be done, haha

@nelser1160 3 года назад

Haha, almost as if we need to know how to derive the formula by completing the square

@aspenrebel 3 года назад

YES! But he's teaching ANOTHER METHOD of solving it. So now you have 2 ways to solve it.

@ttaddasi 5 лет назад

左辺を因数分解すると　　　　　　(2x-1)(x＋4)＝0よって　　　ｘ＝1/2、　　ｘ＝-4　　　　面倒なことをしなくても簡単に解ける

@johnkusters1969 4 года назад

precies , gewoon buiten de haken brengen.

@frogmonger6916 Год назад

not my ass in calculus II having forgot this lmao

@BH-2023 3 года назад

The thing I hated about whenever any maths teacher introduces solving a quadratic by completing the square is that they choose a quadratic that is more efficiently solved by factoring by grouping than by completing the square

@meh.7640 3 года назад

Yeah i was thinking that the whole time. Would‘ve solved that in half the time xD But i guess it‘s for better understanding of the method that the equation is kept simple. So you don‘t get confused by anything else