Algebra Examples

$\frac{x^{2} + 3 x - 18}{x + 9}$

Step 1

Set $\frac{x^{2} + 3 x - 18}{x + 9}$ equal to $0$ .

$\frac{x^{2} + 3 x - 18}{x + 9} = 0$

Step 2

Solve for $x$ .

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Step 2.1

Set the numerator equal to zero.

$x^{2} + 3 x - 18 = 0$

Step 2.2

Solve the equation for $x$ .

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Step 2.2.1

Factor $x^{2} + 3 x - 18$ using the AC method.

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Step 2.2.1.1

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 $- 18$ and whose sum is $3$ .

$- 3, 6$

Step 2.2.1.2

Write the factored form using these integers.

$(x - 3) (x + 6) = 0$

Step 2.2.2

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

$x - 3 = 0$

$x + 6 = 0$

Step 2.2.3

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

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Step 2.2.3.1

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

$x - 3 = 0$

Step 2.2.3.2

Add $3$ to both sides of the equation.

$x = 3$

Step 2.2.4

Set $x + 6$ equal to $0$ and solve for $x$ .

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Step 2.2.4.1

Set $x + 6$ equal to $0$ .

$x + 6 = 0$

Step 2.2.4.2

Subtract $6$ from both sides of the equation.

$x = - 6$

Step 2.2.5

The final solution is all the values that make $(x - 3) (x + 6) = 0$ true.

$x = 3, - 6$

Step 3