MATHEMATICS · Single correct · A Level · Mathematics · Differentiation · Differentiation
Problem
If f′(1)=1 and dxd(f(2x))=f′(x) for all x>0, and if f′(x) is differentiable, then there exists a number c∈(2,4) such that f′′(c) is equal to
(1) −41
(2) −81
(3) 41
(4) 81