Answers and Explanations

PRACTICE TEST 4

1 . E

Since   this    is  an  absolute    value   inequality, you must    solve   two related inequalities,

and  .  Both    of  these   inequalities    hold    when    

Inequality  1:  

Inequality  2:  

So  the solution    to  the inequality  is   or 

2 . C

f(a)    =   |   4a  |   −    2 a^3 .    To  find    the possible    values  of  a,  solve   the absolute    value   equation    |    4 a    |   −

2 a^3   =   66. If  |   4a  |   −   2a^3    =    66 ,   then     4 a    −    2 a^3  =   66  and −4a −   2a^3    =   66. Plug    the values  of  the

answer  options into    each    of  the equations   until   you find    one that    works,  starting    with    the

middle  value:  −4(−3)  −   2(−3)^3     =   12  +   54  =    66 .   So  a   =   −3  is  one possible    value.

3 . E