Cracking The Ap Calculus ab Exam 2018

(Marvins-Underground-K-12) #1
from    part    (b) and solve   for the x-values    when    f′′(x)  =   24x^2   +   12  =   0.  So, x   =       and x   =   −   

. To determine the y-coordinates for these points of inflection, determine f(x) at each of


these    points:    f =  and    f =  .   So  the     points  of  inflection  occur   at 

    and .


  1. Consider the curve given by x^3 y^2 − 5x + y = 3.


(a) Find    .

Use implicit    differentiation:    2x^3 y  +   3x^2 y^2    −   5   +       =   0.  Simplify    and isolate  :      =   

.

(b) Find    .

Use the derivative  from    part    (a) and differentiate   again   using   implicit    differentiation:        =   

. Replace the value for from part (a) for the final


solution:

No  need    to  simplify.

(c) Find    the equation    of  the normal  lines   at  each    of  the two points  on  the curve   whose   x-
coordinate is −1.

From    the original    equation,   at  x   =   −1, y   =   −2  or  y   =   1.  Plug    those   values  into        from    part    (a)
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