Let be a differentiable function with for all

MATHEMATICS · Multi-part · AP · Calculus AB · Differentiation: Composite, Implicit, and Inverse Functions · Differentiation: Composite, Implicit, and Inverse Functions

Problem

Let f(x)f(x) be a differentiable function with f(x)>0f(x)>0 for all xx. Answer the following: (i) Write ddx[ln⁡(f(x))]\dfrac{d}{dx}\bigl[\ln(f(x))\bigr] in terms of f(x)f(x) and f′(x)f'(x). (ii) State one reason for the form of your answer in part (i).

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