Question

If f(x) = x2 / (4 + x), find f ''(5).

Answer 1

The first derivative is found using the quotient rule.

f'(x) = [x(x+8)] / [(x+4)^2]

The second derivative is found using the product rule.

f''(x) = [32] / [(x+4)^3]

f''(5) = [32] / {[(5)+4]^3}