Cracking The Ap Calculus ab Exam 2018

(Marvins-Underground-K-12) #1

ANSWERS AND EXPLANATIONS TO SECTION I



  1. A First, use implicit differentiation to find :


x^2     +   2xy =   0

Isolate     and simplify:

Next,   take    the second  derivative  via implicit    differentiation:

Plug    in      and simplify:


  1. C When y = ln u, = . For this problem, u = 6x^3 − 2x^2 and = 18x^2 − 4x. Then, =


.


  1. D When you insert ∞ for x, the limit is , which is indeterminate. First, rewrite the limit as

    . Then, use L’Hôpital’s Rule to evaluate the limit: . This limit exists and equals


0.


  1. C In order to approximate the error in the volume of the sphere use the approximation formula: dy

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