Cracking The Ap Calculus ab Exam 2018

(Marvins-Underground-K-12) #1

ANSWERS AND EXPLANATIONS TO SECTION I


1. B First, take the antiderivative: ∫ cos(2t) dt = sin(2t).


Next,   plug    in  x   and     for t   and take    the difference:     sin(2x) −   sin.

This    can be  simplified  to  .


  1. D In order to find the inflection point(s) of a polynomial, we need to find the values of x where
    its second derivative is zero.


First,  we  find    the first   and second  derivative.

    =   3x^2    −   30x +   33

    =   6x  −   30

Now,    let’s   set the second  derivative  equal   to  zero    and solve   for x.

6 x −   30  =   0;  x   =   5

In  order   to  find    the y-coordinate,   we  plug    in  5   for x   in  the original    equation.

y   =   5^3     −   15(5^2 )    +   33(5)   +   100 =   15

Therefore,  the coordinates of  the point   of  inflection  are (5, 15).


  1. B We need to use implicit differentiation to find .


6 x −       +   3   =   0

6 x −   2x  −   2   y   +   3   =   0

Now,    if  we  wanted  to  solve   for     in  terms   of  x   and y,  we  would   have    to  do  some    algebra to
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