Find the Vertex Form x^2+2x-120

$x^{2} + 2 x - 120$

Step 1

Write $x^{2} + 2 x - 120$ as an equation.

$y = x^{2} + 2 x - 120$

Step 2

Complete the square for $x^{2} + 2 x - 120$ .

Use the form $a x^{2} + b x + c$ , to find the values of $a$ , $b$ , and $c$ .

$a = 1$

$b = 2$

$c = - 120$

Consider the vertex form of a parabola.

$a {(x + d)}^{2} + e$

Find the value of $d$ using the formula $d = \frac{b}{2 a}$ .

Substitute the values of $a$ and $b$ into the formula $d = \frac{b}{2 a}$ .

$d = \frac{2}{2 \cdot 1}$

Cancel the common factor of $2$ .

Cancel the common factor.

$d = \frac{2}{2 \cdot 1}$

Rewrite the expression.

$d = 1$

Find the value of $e$ using the formula $e = c - \frac{b^{2}}{4 a}$ .

Substitute the values of $c$ , $b$ and $a$ into the formula $e = c - \frac{b^{2}}{4 a}$ .

$e = - 120 - \frac{2^{2}}{4 \cdot 1}$

Simplify the right side.

Simplify each term.

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

$e = - 120 - \frac{4}{4 \cdot 1}$

Multiply $4$ by $1$ .

$e = - 120 - \frac{4}{4}$

Cancel the common factor of $4$ .

Cancel the common factor.

$e = - 120 - \frac{4}{4}$

Rewrite the expression.

$e = - 120 - 1 \cdot 1$

Multiply $- 1$ by $1$ .

$e = - 120 - 1$

Subtract $1$ from $- 120$ .

$e = - 121$

Substitute the values of $a$ , $d$ , and $e$ into the vertex form ${(x + 1)}^{2} - 121$ .

${(x + 1)}^{2} - 121$

Step 3

Set $y$ equal to the new right side.

$y = {(x + 1)}^{2} - 121$