Evaluate Using the Given Value 9x-2y^2 ; x=3 , y=-4

$9 x - 2 y^{2}$ ; $x = 3$ , $y = - 4$

Replace the variable $x$ with $3$ in the expression.

$9 (3) - 2 y^{2}$

Replace the variable $y$ with $- 4$ in the expression.

$9 (3) - 2 {(- 4)}^{2}$

Simplify each term.

Multiply $9$ by $3$ .

$27 - 2 {(- 4)}^{2}$

Raise $- 4$ to the power of $2$ .

$27 - 2 \cdot 16$

Multiply $- 2$ by $16$ .

$27 - 32$

Subtract $32$ from $27$ .

$- 5$