Write in Standard Form (x+6)^2=15

${(x + 6)}^{2} = 15$

Subtract $15$ from both sides of the equation.

${(x + 6)}^{2} - 15 = 0$

Simplify ${(x + 6)}^{2} - 15$ .

Simplify each term.

Rewrite ${(x + 6)}^{2}$ as $(x + 6) (x + 6)$ .

$(x + 6) (x + 6) - 15 = 0$

Expand $(x + 6) (x + 6)$ using the FOIL Method.

Apply the distributive property.

$x (x + 6) + 6 (x + 6) - 15 = 0$

Apply the distributive property.

$x \cdot x + x \cdot 6 + 6 (x + 6) - 15 = 0$

Apply the distributive property.

$x \cdot x + x \cdot 6 + 6 x + 6 \cdot 6 - 15 = 0$

Simplify and combine like terms.

Simplify each term.

Multiply $x$ by $x$ .

$x^{2} + x \cdot 6 + 6 x + 6 \cdot 6 - 15 = 0$

Move $6$ to the left of $x$ .

$x^{2} + 6 \cdot x + 6 x + 6 \cdot 6 - 15 = 0$

Multiply $6$ by $6$ .

$x^{2} + 6 x + 6 x + 36 - 15 = 0$

Add $6 x$ and $6 x$ .

$x^{2} + 12 x + 36 - 15 = 0$

Subtract $15$ from $36$ .

$x^{2} + 12 x + 21 = 0$

To write a polynomial in standard form, simplify and then arrange the terms in descending order.

$a x^{2} + b x + c = 0$

The standard form is $x^{2} + 12 x + 21$ .

$x^{2} + 12 x + 21 = 0$