Find the Vertex Form -2x^2+4x-5

$- 2 x^{2} + 4 x - 5$

Step 1

Write $- 2 x^{2} + 4 x - 5$ as an equation.

$y = - 2 x^{2} + 4 x - 5$

Step 2

Complete the square for $- 2 x^{2} + 4 x - 5$ .

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

$a = - 2$

$b = 4$

$c = - 5$

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 $d = \frac{b}{2 a}$ .

$d = \frac{4}{2 \cdot - 2}$

Simplify the right side.

Cancel the common factor of $4$ and $2$ .

Factor $2$ out of $4$ .

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

Cancel the common factors.

Factor $2$ out of $2 \cdot - 2$ .

$d = \frac{2 \cdot 2}{2 (- 2)}$

Cancel the common factor.

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

Rewrite the expression.

$d = \frac{2}{- 2}$

Cancel the common factor of $2$ and $- 2$ .

Factor $2$ out of $2$ .

$d = \frac{2 (1)}{- 2}$

Move the negative one from the denominator of $\frac{1}{- 1}$ .

$d = - 1 \cdot 1$

Multiply $- 1$ by $1$ .

$d = - 1$

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 $e = c - \frac{b^{2}}{4 a}$ .

$e = - 5 - \frac{4^{2}}{4 \cdot - 2}$

Simplify the right side.

Simplify each term.

Cancel the common factor of $4^{2}$ and $4$ .

Factor $4$ out of $4^{2}$ .

$e = - 5 - \frac{4 \cdot 4}{4 \cdot - 2}$

Cancel the common factors.

Factor $4$ out of $4 \cdot - 2$ .

$e = - 5 - \frac{4 \cdot 4}{4 (- 2)}$

Cancel the common factor.

$e = - 5 - \frac{4 \cdot 4}{4 \cdot - 2}$

Rewrite the expression.

$e = - 5 - \frac{4}{- 2}$

Cancel the common factor of $4$ and $- 2$ .

Factor $2$ out of $4$ .

$e = - 5 - \frac{2 (2)}{- 2}$

Move the negative one from the denominator of $\frac{2}{- 1}$ .

$e = - 5 - (- 1 \cdot 2)$

Multiply $- (- 1 \cdot 2)$ .

Multiply $- 1$ by $2$ .

$e = - 5 - - 2$

Multiply $- 1$ by $- 2$ .

$e = - 5 + 2$

Add $- 5$ and $2$ .

$e = - 3$

Substitute the values of $a$ , $d$ , and $e$ into the vertex form $- 2 {(x - 1)}^{2} - 3$ .

$- 2 {(x - 1)}^{2} - 3$

Step 3

Set $y$ equal to the new right side.

$y = - 2 {(x - 1)}^{2} - 3$

Find the Vertex Form -2x^2+4x-5

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