#### Answer

$20$

#### Work Step by Step

RECALL:
$f(a)$ represents the value of the function $f$ when $x=a$.
Thus, $f(-2)$ represents the value of the function $f$ when $x=-2$.
Substitute $-2$ to $x$ in the function $f$ to obtain:
$f(-2) = (-2)^2-5(-2)+6
\\f(-2)=4-(-10)+6
\\f(-2)=4+10+6
\\f(-2)=20$