Cracking The Ap Calculus ab Exam 2018

(Marvins-Underground-K-12) #1
slope,  m:      =   −39.    Finally,    we  plug    in  the point   (5, −29)    and the slope   m   =

−39 to  get the equation    of  the tangent line:   y   +   29  =   −39(x   −   5).


  1. y − 7 = (x − 4)


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 slope   by  plugging    x   =   4   into    the derivative  of  the equation    y   =    .  First,  we

take    the derivative:     =    .  Now,    we  can find    the slope,  m:  

    =    .  Finally,    we  plug    in  the point   (4, 7)  and the slope   m   =       to  get the

equation    of  the tangent line:   y   −   7   =    (x −   4).


  1. x = ±


The slope   of  the line    y   =   x   is  1,  so  we  want    to  know    where   the slope   of  the tangent line    is  equal

to  1.  We  find    the slope   of  the tangent line    by  taking  the derivative:     =   6x^2    −   8.  Now we  set

the derivative  equal   to  1   :   6x^2    −   8   =   1.  If  we  solve   for x,  we  get x   =   ±.


  1. y − 7 = (x − 3)


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   =   3   into    the equation    y   =    ,  and we  find    the slope

by  plugging    x   =   3   into    the derivative  of  the equation.

First,  we  find    the y-coordinate,   y 1     :   y   =       =   7.  This    means   that    the line    passes  through the

point   (3, 7).

Next,    we  take    the     derivative:     =   .   Now,    we  can     find    the

slope,  m:      =   −2. However,    this    is  the slope   of  the tangent line.   The normal  line
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