Quick help please with questions

I have set up the differential equation for part a) and now I have to integrate it but the mark scheme is saying that for the left hand side it’s -ln[100-p] but I got ln[100-p] so I just need an explanation of where the minus sign comes from.

Reply 1

mqb2766

Original post by Matheen1

you probably forgot that you need a fraction like
f'(x)/f(x)
to integrate to ln(|f(x)|), so you need a numerator of -1. But without working ...

Reply 2

Matheen1

Original post by mqb2766

you probably forgot that you need a fraction like
f'(x)/f(x)
to integrate to ln(|f(x)|), so you need a numerator of -1. But without working ...

This is what I have and it differentiates to ln[100-p] not -ln[100-p] as required

Reply 3

mqb2766

As per the previous post you need a numerator of -1 as this is the derivative of the denomiator so use 1 = (-1)*(-1), and pull one of hte -1s outside the integral