Cracking The Ap Calculus ab Exam 2018

(Marvins-Underground-K-12) #1
We  find    the derivative  using   the Product Rule,   which   says    that    if  f(x)    =   uv, then    f′(x)   =   u   +   v

. Here f(x) = (x^4 − x^2 )(2x^3 + x), so u = x^4 − x^2 and v = 2x^3 + x. Using the Product Rule, we


get f′(x)   =   (x^4    −   x^2 )(6x^2  +   1)  +   (2x^3   +   x)(4x^3     −   2x).    Now we  don’t   simplify.   We  simply  plug    in  x

=   1   to  get f′(x)   =   ((1)^4  −   (1)^2 )(6(1)^2  +   1)  +   (2(1)^3     +   (1))(4(1)^3     −   2(1))   =   6.

14.

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

. Here f(x) = , so u = x^2 + 2x and v = x^4 − x^3 . Using the Quotient Rule, we


get f′(x)   =    .  Now,    we  don’t   simplify.   We  simply  plug    in  x   =   2

to  get.    f′(x)   =       =   −.

15.

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

. Here f(x) = = (x^4 + x^2 ). Using the Chain Rule, we get f′(x) = (x^4


+   x^2 )   (4x^3   +   2x).    This    can be  simplified  to  f′(x)   =   .

16.

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

. Here = 2u and = −1(x − 1)−2 = − . Thus, = (2u) and


because u   =    ,      =       =   −.

17. −24

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