Cracking The Ap Calculus ab Exam 2018

(Marvins-Underground-K-12) #1
take    the derivative:     =   −   3   −   2x. Now,    we  can find    the slope,  m:      =   −   3   −   3(0)    =   −   3.

Finally,    we  plug    in  the point   (0, 4)  and the slope   m   =   −3  to  get the equation    of  the tangent line:

y   −   4   =   −3(x    −   0)  or  y   =   −   3x  +   4.


  1. y = 0


Remember    that    the equation    of  a   line    through a   point   (x 1 ,  y 1 )   with    slope   m   is  y   −   y 1     =   m   (x  −
x 1 ). We find the y-coordinate by plugging x = −2 into the equation y = (x^2 + 4x + 4)^2 , and we
find the slope by plugging x = −2 into the derivative of the equation.

First,  we  find    the y-coordinate,   y 1     :   y   =   ((−2)^2     +   4(−2)   +   4)^2    =   0.  This    means   that    the line

passes  through the point   (−2,    0).

Next,   we  take    the derivative:     =   2(x^2   +   4x  +   4)(2x   +   4). Now,    we  can find    the slope,  m:  

    (2(−2)  +   4)  =   0.  Finally,    we  plug    in  the point   (−2,    0)  and the

slope   m   =   0   to  get the equation    of  the tangent line:   y   −   0   =   0(x +   2)  or  y   =   0.

4.

The  Mean    Value   Theorem     says    that    if f(x)     is  continuous  on  the     interval    [a,    b]   and     is

differentiable  everywhere  on  the interval    (a, b), then    there   exists  at  least   one number  c   on  the

interval    (a, b)  such    that     .  Here,   the function    is  f(x)    =   x^3     +   12x^2   +   7x  and

the  interval    is  [−4,    4].     Thus,   the     Mean    Value   Theorem     says    that    f′(x)   =  

. This simplifies to f′(c) = 23. Next,


we  need    to  find    f′(c).  The derivative  of  f(x)    is  f′(x)   =   3x^2    +   24x +   7,  so  f′(c)   =   3c^2    +   24c +   7.

Now,     we  can     solve   for     c:  3c^2 +  24c     +   7   =   23  and     .   Note    that   

    is  in  the interval    (−4,    4), but     is  not in  the interval.   Thus,   the
Free download pdf