Question

Find the global maximum of the function:
f(x) = -x^4 +16x^3 -40x^2 -1742

global maximum = _____

Answer 1

I know when the concavity of the f changes at an inflection point, the sign of f" changes, so the inflection point is 0 or undefined.

I also know f'(x) = -4x^3 + 48x^2 -80x

Answer 2

I know f(x) generally looks like this, but 10 isn't the answer?