Find the Vertex y=(x+4)(x-2)

$y = (x + 4) (x - 2)$

Step 1

Rewrite the equation in vertex form.

Complete the square for $(x + 4) (x - 2)$ .

Simplify the expression.

Expand $(x + 4) (x - 2)$ using the FOIL Method.

Apply the distributive property.

$x (x - 2) + 4 (x - 2)$

Apply the distributive property.

$x \cdot x + x \cdot - 2 + 4 (x - 2)$

Apply the distributive property.

$x \cdot x + x \cdot - 2 + 4 x + 4 \cdot - 2$

Simplify and combine like terms.

Simplify each term.

Multiply $x$ by $x$ .

$x^{2} + x \cdot - 2 + 4 x + 4 \cdot - 2$

Move $- 2$ to the left of $x$ .

$x^{2} - 2 \cdot x + 4 x + 4 \cdot - 2$

Multiply $4$ by $- 2$ .

$x^{2} - 2 x + 4 x - 8$

Add $- 2 x$ and $4 x$ .

$x^{2} + 2 x - 8$

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

$a = 1$

$b = 2$

$c = - 8$

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

$e = - 8 - \frac{2^{2}}{4 \cdot 1}$

Simplify the right side.

Simplify each term.

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

$e = - 8 - \frac{4}{4 \cdot 1}$

Multiply $4$ by $1$ .

$e = - 8 - \frac{4}{4}$

Cancel the common factor of $4$ .

Cancel the common factor.

$e = - 8 - \frac{4}{4}$

Rewrite the expression.

$e = - 8 - 1 \cdot 1$

Multiply $- 1$ by $1$ .

$e = - 8 - 1$

Subtract $1$ from $- 8$ .

$e = - 9$

Substitute the values of $a$ , $d$ , and $e$ into the vertex form ${(x + 1)}^{2} - 9$ .

${(x + 1)}^{2} - 9$

Set $y$ equal to the new right side.

$y = {(x + 1)}^{2} - 9$

Step 2

Use the vertex form, $y = a {(x - h)}^{2} + k$ , to determine the values of $a$ , $h$ , and $k$ .

$a = 1$

$h = - 1$

$k = - 9$

Step 3

Find the vertex $(h, k)$ .

$(- 1, - 9)$

Step 4

Find the Vertex y=(x+4)(x-2)

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