yea thats the answer but im 99% you would lose marks because
ln(a+b+c)=ln(a)+ln(b)+ln(c) but yet youve used it in your working, and it only didnt matter because
y=e2Think of it like having to find x when
x=22, if you do
x=2×2 you still get the right answer but you're working it wrong and you've just fluked it, that's kind of similar to whats happened here.
My previous post includes 2 ways of doing it,
http://www.thestudentroom.co.uk/showpost.php?p=67855350&postcount=875.
Another way is to get to
ln(e5−e2+y)+lny=7 then "e" both sides to get;
eln(e5−e2+y)+lny=e7you'll then get a quadratic to solve