Hello everyone! I am having some trouble working out this question:

If a marginal cost function nis c'(q)=6q^2+880 dollars per unit, then the cost to increase production from 6 units to 9 units is ...

I did this question in 2 ways. One of which I may have found a fault in my steps.

1) Take q=9 and q=6, sub into the marginal cost function and subtract q=9 from q=6. Personally, I don't see how that can give a reasonable answer, but it was worth a shot.

2) Integrate (although this type of question was around before I learned it) and sub in q=6 and q=9 for c(q) and subtract.

So I was wondering, if that is how you should go about doing the questions or what I should do.

And on the lines of that, another question was bugging me.

If for all real x we assume f(g(x)) = x and f'(x) = 1+ [f(x)]^2, then g'(0) equals .. I came up with the answer of: 1

Thanks!