Answer
$b^{2}-4ac=76$
Work Step by Step
$a=3,b=2,c=-6$
$ b^{2}-4ac\qquad$ ...substitute $3$ for $a,\ 2$ for $b$ and $-6$ for $c$.
$=(2)^{2}-4\cdot 3\cdot(-6)\qquad$ ...evaluate $(2)^{2}$
$=4-4\cdot 3\cdot(-6)\qquad$ ...multiply before subtracting
$=4+72$
$=76$
