Casio fx-991EX and fx-991CW tips for A level and GCSE maths students who want to boost their calculator skills - a quick win to help with your maths work. This channel also provides help for GCSE resit students who want to 'Maximise Maths Marks' and for year 1/ AS maths students who want pure maths help.
I am a qualified and experienced teacher with a maths degree. Each video has been checked by another maths teacher to ensure there are no accidental mistakes. If you do spot an error, or anything that is not clear, then please flag it up via a comment. Thank you.
That's on the inner scale. We are using the outer scale as we have positioned the protractor so that 0 degrees on the outer scale is lined up with one side of the angle :)
Good video. However, the generalised writing for all odd numbers as 2n+1 for any natural number n is not correct since it excludes the number 1 from the set of odd numbers.
Thank you for flagging this up! You're absolutely right, the 2n+1 form does exclude the value 1 from the proof. The value 1, being 1 more than the zeroth multiple of 4, could be included separately in the version of the proof in the video, or alternatively the proof could be based on the general form 2n-1 instead.
Thanks! I just have one question, we proved that lambda is half which shows that OE is half of OB, thus E is the midpoint for the OB diagonal but do we have to do it for the AC diagonal too or can it be assumed that since its the midpoint for one diagonal then it is for the other too? Thanks!
Thank you for your question. In the video we set the fraction along OE as lambda and the fraction along AC as mu at which the diagonals intersect. Then we show that lambda is a half but also at 3.45 mins into the video that lambda = mu. So we don't assume that that the point of intersection halves the diagonal AC as we also show that mu is a half too.
@@helenmathstutor I got a way might be useful for you at ti 84 calculator click 2nd , X-1, math, 8 rref(, alpha, zoom, then put whatever numbers in the equations at row and col. This method called rref
@@helenmathstutor The equations I have are specifically 0.2x+y=180000 and 1-0.1y=200000. So when I input the coefficient of x and y, it gives me math error
I don't think there's a way to do it on this calculator. Sub the first equation into the second and then solve the resulting quadratic equation is how you do it on paper. Good luck!
You can't complete the square diectly on this calculator, but you can use it to find the roots and the turning point. These two pieces of information would allow you write down the completed square form.
One way would be to take the given function, y = f(x) and re-write it in the form x = f(y). The limits would also need to be converted to the corresponding values for y. Then you could use the calculator in the same way as before.
Thank you for your question. If you would like to know how to summarise in words what the proof shows, then the conclusion can be found in the video between 3.56 and 4.15
