Cracking The Ap Calculus ab Exam 2018

(Marvins-Underground-K-12) #1
get f′(x)   =    .  This    can be  simplified  to  f′(x)   =   .

22. 0

Here    we  will    find    the derivative  using   the Chain   Rule.   We  will    also    need    the Quotient    Rule    to

take    the derivative  of  the expression  inside  the parentheses.    The Chain   Rule    says    that    if  y   =

f(g(x)),     then   y′   =      and the Quotient     Rule    says    that    if f(x)     =   ,   then   f′(x)    =  

. We get f′(x) = . Now we don’t simplify. We


simply  plug    in  x   =   1   to  get f′(x)   =       =   0.

23.

We   find    the     derivative  using   the     Quotient    Rule,   which   says    that    if f(x)     =   ,   then   f′(x)    =  

. We will also need the Chain Rule to take the derivative of the expression in the


denominator.    The Chain   Rule    says    that    if  y   =   f(g(x)),    then    y′=  .   Here   f(x)     =  

,   so  u   =   x   and v   =   (1  +   x^2 )^2 .   We  get f(x)    =    .  Now we  don’t

simplify.   We  simply  plug    in  x   =   1   to  get f(x)    =       =   −.

24.

We  find    the derivative  using   the Chain   Rule,   which   says    that    if  y   =   y(v)    and v   =   v(x),   then    

. Here and . Now, we plug v = 2 into


the  derivative.     Note    that,   where  v    =   2, x    =   .   We  get     +   +  

    and  ,  so  .


  1. −4 csc^2 (4x)

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