## Precalculus: Concepts Through Functions, A Unit Circle Approach to Trigonometry (3rd Edition)

$a = -2$
$f(-1) = (-1)^{2}a + 4 \\f(-1) = 1(a^2)+4 \\f(-1)=a^2+4$ Since $f(-1) = 2$, then $f(-1)=a^2+4 \\2 = a + 4 \\2-4=a \\-2=a$