Find the Perfect Square Trinomial x^2+18x+c

$x^{2} + 18 x + c$

Move $18 x$ .

$x^{2} + c + 18 x$

To find the $c$ value $c = {(\frac{b}{2})}^{2}$ , divide the coefficient of $x$ by $2$ and square the result.

Divide $18$ by $2$ .

$9^{2}$

Raise $9$ to the power of $2$ .

$81$