y=f(g(x))-g(x^2+1) at x=1

f(x) = 3 g(x) = 2 f'(x)= -2 g'(x) = 4

I have to find the derivative and use these values to calculate the answer, at x=1.

I go the derivative to be

f'(x)g(x)*g'(x) - g'(x^2+1) *2x (I know this is right)

Plugging in I got -2*2*4 - g'(x^2+1) * 2

The answer is -24 and I have no clue how to evaluate g'(x^2+1), i think it has to evaluate to 4 for the answer to make sense

All help appreciated! Thanks!