Cracking The Ap Calculus ab Exam 2018

(Marvins-Underground-K-12) #1
expression  into    the area    formula.    First   isolate y   =    ,  then    plug    in: A   =   x^2     +   4x  =   x^2     +   

. Now we take the derivative A′ = 2x −


Set the derivative  equal   to  zero    and solve:

2 x −       =   0

2 x^3   −   2000    =   0

x^3     =   1000

x   =   10  ft

The dimensions  of  the base    are 10  feet    by  10  feet.


  1. First, we need to find the slope of the tangent line to y = . This is the derivative: y′ =

    . Now, to find where the slope is the greatest, we take the derivative and set it equal


to  zero.   We  get y′′ =       =   0,  which   can be  simplified  to  

= 0.

Note    that    we  just    need    to  solve   for where   the numerator   is  0.  Let’s   simplify    the numerator:

−2  −   2x^2    +   8x^2    =   0
−2 + 6x^2 = 0

We  can solve   for x:  x   =   ± . If  we  plug    these   two values  into    the equation    for the slope   we

find    that    at  x   =    ,  y′  =   
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