Cracking The Ap Calculus ab Exam 2018

(Marvins-Underground-K-12) #1
the h   in  the denominator:    f′(−3)  =    (54    −   18h +   2h^2 ). Now we  take

the limit   to  get f′(−3)  =       (54 −   18h +   2h^2 )  =   54.


  1. −9x^2


We  find    the derivative  of  a   function,   f(x),   using   the definition  of  the derivative, which   is  f′(x)   =   

. Here, f(x) = −3x^3 . This means that f(x + h) = −3(x + h)^3 = −3(x^3 + 3x^2 h


+   3xh^2   +   h^3 )   =   −3x^3   −   9x^2 h  −   9xh^2   −   3h^3.

If  we  now plug    these   into    the definition  of  the derivative, we  get f′(x)   =   

=    .   This    simplifies  to  f′(x)   =  

. Now we can factor out the h from the numerator and cancel it with


the h   in  the denominator:    f′(x)   =       =    (−9x^2     −   9xh −   3h^2 ). Now we

take    the limit   to  get f′(x)   =    (−9x^2     −   9xh −   3h^2 )  =   −9x^2.


  1. 5 x^4


We  find    the derivative  of  a   function,   f(x),   using   the definition  of  the derivative, which   is  f′(x)   =   

. Here f(x) = x^5.


This    means   that    f(x +   h)  =   (x  +   h)^5    =   (x^5    +   5x^4 h  +   10x^3 h^2   +   10x^2 h^3   +   5xh^4   +   h^5 ).  If  we  now plug

these    into    the     definition  of  the     derivative,     we  get     f′(x)   =   =  

.

This    simplifies  to  f′(x)   =    .  Now we  can factor  out

the  h   from    the     numerator   and     cancel  it  with    the     h   in  the     denominator:    f′(x)   =  

    =       (5x^4   +   10x^3 h +   10x^2 h^2   5 xh^3  +   h^4 ).  Now we

take    the limit   to  get f′(x)   =    (5x^4  +10x^3 h    +   10x^2 h^2   +   5xh^3   +   h^4 )   =   5x^4.
Free download pdf