Find the Perfect Square Trinomial x^2+21x

$x^{2} + 21 x$

Step 1

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

Apply the product rule to $\frac{21}{2}$ .

$\frac{21^{2}}{2^{2}}$

Raise $21$ to the power of $2$ .

$\frac{441}{2^{2}}$

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

$\frac{441}{4}$

Step 2

Add $\frac{441}{4}$ to get the perfect square trinomial.

$x^{2} + 21 x + \frac{441}{4}$