Edexcel A2 C4 Mathematics June 2016 - Official Thread

Yeah as it doesn't ask for what the maximum is or anything, just asks you to show that it doesn't "exceed" 5000. I guess that should imply an inequality

are u the one that runs the physicsmaths tutor website

If a population is modelled by $P= \frac{25}{5+20e^{-\frac{1}{3}t}}$ and you have to show that the population never exceeds 5000. (P is in thousands)

But the mark scheme says award B0 for: as $t\rightarrow\infty, p\rightarrow \frac{25}{5}$

Unless you show that it is an increasing function, I don't want to take the long winded route for 1 mark, so how would I show the maximum value of P? As I don't really understand what's going on in the mark scheme.

180 over both of them.

Ah, thank you. My teacher insisted that in the scenario where you got 89 on one of them and 91 on the other, you wouldn't get an A*.

He's definitely wrong. I know of one user on here who got 85 on C3 and 100 on C4 and got his A*.

Also, Zacken, I saw you did solutions for this year's C2 exam, will you be doing the same for C3 and C4?

I was going to but someone else is doing them instead. I'll be doing FP2 and FP3.

Which paper is this from?

Ah, thank you. My teacher insisted that in the scenario where you got 89 on one of them and 91 on the other, you wouldn't get an A*.

I got 100 in C3 and 84 in C4 because C4 is icky. but still got an A*

I'm not a fan of C4 either Much prefer C3. Although, after doing loads of practice, my integration is getting up to scratch

Yes... just don't forget how to find the volume of a rotated solid or whatever (which is what I did and lost all the marks on that question )

and vectors as well.. icky.. but draw diagrams, practice, and make sure you get as many marks as possible

quick question, if u can integrate functions via the reverse chain rule, why can't u integrate trigonometric functions by the reverse chain rule. For example : sin^2.

1/3 sin^3. 1/cosx?
yh that doesn't work, but why?

Yeah... that's why I'm afraid I cannot offer an explanation

However, a few things to note.

If you have something icky in terms of trig that you need to integrate, you can use different formulae (eg factor formula, double angle formula, stuff in your formula bloklet) to change it into something that is easier to integrate, like coskx where k is a number - you know that the integral of that is 1/k * sinkx.

Also, you can use the reverse chain rule or whatever to integrate things like
$\sin^2 \theta + \cos^2 \theta=1$

...latex in progress.