Answer
a) 0
b) $\frac{-45}{4}$
c) f(a)=a^2-a-12
d) $\frac{4}{m^2}-\frac{2}{m}-12$
e) $x=\frac{1\pm\sqrt 53}{2}$
Work Step by Step
$f(x)=(x+3)(x-4)$
$=x^2-x-12$
$a) f(4) =(4)^2-4-12=0$
$b) f(\frac{-1}{2})=(\frac{-1}{2})^2-(\frac{-1}{2})-12=\frac{-45}{4}$
$c) f(a)=a^2-a-12$
$d) f(\frac{2}{m})=(\frac{2}{m})^2-\frac{2}{m}-12=\frac{4}{m^2}-\frac{2}{m}-12$
e) $f(x)=1$
$x^2-x-12=1$
$x^2-x-13=0$
$x=\frac{1\pm\sqrt 53}{2}$
