Algebra Examples

$x^{2} + 9 x = 36$

Step 1

Subtract $36$ from both sides of the equation.

$x^{2} + 9 x - 36 = 0$

Step 2

Factor $x^{2} + 9 x - 36$ using the AC method.

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Consider the form $x^{2} + b x + c$ . Find a pair of integers whose product is $c$ and whose sum is $b$ . In this case, whose product is $- 36$ and whose sum is $9$ .

$- 3, 12$

Write the factored form using these integers.

$(x - 3) (x + 12) = 0$

Step 3

If any individual factor on the left side of the equation is equal to $0$ , the entire expression will be equal to $0$ .

$x - 3 = 0$

$x + 12 = 0$

Step 4

Set $x - 3$ equal to $0$ and solve for $x$ .

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Set $x - 3$ equal to $0$ .

$x - 3 = 0$

Add $3$ to both sides of the equation.

$x = 3$

Step 5

Set $x + 12$ equal to $0$ and solve for $x$ .

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Set $x + 12$ equal to $0$ .

$x + 12 = 0$

Subtract $12$ from both sides of the equation.

$x = - 12$

Step 6

The final solution is all the values that make $(x - 3) (x + 12) = 0$ true.

$x = 3, - 12$