Learn how to Solve Logarithmic Equations with different bases using the Change of Base Formula. Also check your answer for extraneous solutions. Step-by-Step Explanation by PreMath.com
I love this. One thing I wanted to add to gues video is that being log8(x) and log16(x) have base 2 in common, we could rewrite it as log2^3(x) and log2^4(x) and identifying a log base value would be the denominator when the change of base is applied, we could then rewrite the equation as 1/3log2(x)-1/4log2(x) and then proceed from there.
A man who makes totally time wasting short videos has 10 million subscribers in his channel but this channel is really awesome and has only approx 2 lakh. Not fair yaarrr
00:00 It is even more simple when you use the formula: log.(a^m) (x) = (1/m) * log.a(x) Hence you get: log.8(x) - log.16(x) = 0 log.(2^3)(x) - log.(2^4)(x) = 0 (1/3) * log.2(x) - (1/4) * log.2(x) = 0 Now it is quite simple: [ (1/3) - (1/4) ] * log(x) = 0 [ (4/12) - (3/12) ] * log(x) = 0 (1/12) * log(x) = 0 || *12 log(x) = 0 log.10(x) = 0 x = 10^0 x = 1 "1" is the solution, because it is in the Domain which is D: x>0
I love this. Two logs have different base and are equal. How's that? So that x = 1. Just because no other points where different-base logs can meet. Telling this basic story during nine minutes - great.
There is a short solution. You solve the right side y= log.16 (x) by taken it to the base (2*8) . y is only a placeholder for the watched term. So (2*8)^y=x eq(1). This can be simplified to 2^y*8^y=x (eq2). Now the left side is taken to base 8. So y=log.8 (x) becomes 8^y=x eq(3) , which can be written as 2^y*2^y*2^y=x. Now taken the 3. root from that: 2^y=3.root(x) (eq4) eq(3) and eq(4) we set in eq(2) and we get 3.root(x)*x=x. We can see the possible solution are x=0 and x=1. But x=0 is no solution, because the original equation get infinity. It remains x=1
For those of you telling sir that he could have solved the problem in three steps keep your mouth shut, he's a professor he knows wat he's doing and his intentions was to clearly illustrate for students that might not readily know how to go about solving this problem problem, thank you.
All humans have mistake except Lord Jesus and his mother virgn Mary and being professer doesn't make him knowing every thing and not to do mistake expect tirinty lord
I strongly disagree with you. In an exam students need the shortest possible mathematical way to solve problems. They don't need complicated methods and he being a professor should know that.
Change of base, seems to suggest Gauge equation: unit conversion transform method. Conductance, energy, conversion and energy transform ascertained. Thanks and have a nice day, thank you Sam.
The log function is not defined on the interval ]-∞, 0]. You MUST state that BEFORE begining any calculus, hence excluding 0 as a solution. Thus checking the answer x=0 as you do is unnecessary (not to say wrong).
Hi Sir, just wonder about this part x^4 = x^3, Couldn't you just divide both sides by x^3 so you could find just the true answer right away? Thanks anyway way.
@@war_reimon8343 You must factor it to find all the real solutions x^4 = x^3 x^4 - x^3 = 0 (x^3)(x - 1) = 0 (factoring x^3) The two solutions are: x^3 = 0 or x - 1 = 0 Therefore from the first equation x = 0 and from the second we get x = 1
Hello Eshwaraiah, here is the proof: Our LHS: log a basex=log b base x => use the change of base formula: (loga)/(logx) = (logb)/(logx) => both denominators get cancelled => loga = logb => use equality rule: a=b RHS. Hope it helps. If you want I can upload video for you as well. Take care and all the best😃
What i did at the end where we have: X^⅓ = X^¼ is: Divide both sides by X^¼ X^⅓/X^¼=1 Move the X^¼ to the numerator and get: X^⅓*X^-¼=1 X^1/12=1 (X^1/12)^12=1^12 X=1
Dude! I did it the easier way out. First, what I did is, used the change of base formula ; then rewrote 16 as 2^4, and 8 as 2^3 ; then I used the power rule of logs "log(n^b) = b * log(n)" ; then I multiplied both of the fractions to get common denominators ; then I set just the numerator equal to zero after setting the whole fraction equal to 0 ; then I used the power rule of logs in reverse "b * log(n) = log(n^b)" ; then I used the quotient rule of logs ; then I used the quotient rule of exponents within the logs ; then I set log(x) to be equal to log(x) with base 10 ; then I converted to exponential form ; then noticed 10^0, which is equal to 1, and that is equal to x. What you are doing is the longer way out. you are checking for more possible solutions, but they are extraneous, so it would have been better if you did what I did no?
Form the very begining you can take logx as a common factor then you will see that log x times 1/log8 minus 1/log16 equal zero which means that logx equal to zero therefore x equal 1
I didn't do it that same way but still had an answer. I got to a part of 4INX - 3INX which is equal to zero. Then I subtracted 3 from 4, which which made it e of x is equal to zero. Then I had x to be one.
03:45 You should rather put this "(1/4)*log(x)" form the right side to the left side (with the sign "+" changed to "-"): (1/3)*log(x) = (1/4)*log(x) (1/3)*log(x) - (1/4)*log(x) = 0 [ (1/3) - (1/4) ] * log(x) = 0 [ (4/12) - (3/12) ] * log(x) = 0 (1/12) * log(x) = 0 || *12 log(x) = 0 log.10(x) = 0 x = 10^0 x = 1 "1" is the solution, because it is in the Domain which is D: x>0
So nice of you Ramani dear! You are awesome 👍 I'm glad you liked it! Please keep sharing premath channel with your family and friends. Take care dear and stay blessed😃
Thank you so much luyando mweemba for taking the time to leave this comment. I'm glad you liked it! Your feedback is always appreciated. Please keep supporting my channel. Please stay connected. Take care dear 😃
These people were trying to outsmart the teacher.really? Why waste watching if you know already and know quick solution? ..this lecture is for those students or person who has difficulty and willing to understand it step by step. Just be humble guys, make ur own RU-vid channel..
I think we can solve this problem in another way avoiding all the complicated calculations Logically how can the power of 8 and 16 be same for the same value unless the value is 1 and power is 0 hence x has to be equal to 1
I have a Little doubt, sir At 6:30, you got X⁴ = X³, so as the bases are equal, we get 4 = 3 but 4 ≠ 3, I am a bit confused, could you please reply However, Thank you very much for this amazing video, I have been actively watching a lot of your videos and they have really amazed me! Keep it up! hope to see more!
If you try putting up the value of x as 1 or 0, the equation X³ = X⁴ will become valid, as we know, 1 to the power of n = 1; thus X³ = 1; X⁴ = 1; hence X³=X⁴ And. For x=0, 0^n = 0. Hence X³ =X⁴ =0 This won't work out on other values, except for 0 and 1... Hope you got my point....
It was obvious from the beginning that log x = 0, meaning x = 1, because the only way that raising x to two different powers gives an equality is if x = 1. This fellow used a sledgehammer to kill a fly. Far too complicated, tedious, and unnecessary.
I agree. And whatever the base is, log 0 is undefined, so the solution x=0 must be rejected before any calculus. (Always check the domain before starting !)
God loves you and he wants to save everyone, but in order for him to do that, you need to repent and be baptized. Also share his gospel with everyone you come in to contact with and keep his commandments 🙏🏾😘