12. Find the derivative of f(x) = In x26x3 + 5 Hint: apply the properties of logarithms before differentiating. x 3 + 1 13. Let f(x) = x 2* a. Use logarithmic differentiation to find the derivative of f(x). b. Find the slope of the tangent line to the graph of f (x) at x = 4. Give an exact answer instead of a decimal approximation