Trigonometry Examples

${(x + 3)}^{2} = 81$

Step 1

Take the specified root of both sides of the equation to eliminate the exponent on the left side.

$x + 3 = \pm \sqrt{81}$

Step 2

Simplify $\pm \sqrt{81}$ .

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Step 2.1

Rewrite $81$ as $9^{2}$ .

$x + 3 = \pm \sqrt{9^{2}}$

Step 2.2

Pull terms out from under the radical, assuming positive real numbers.

$x + 3 = \pm 9$

Step 3

The complete solution is the result of both the positive and negative portions of the solution.

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Step 3.1

First, use the positive value of the $\pm$ to find the first solution.

$x + 3 = 9$

Step 3.2

Move all terms not containing $x$ to the right side of the equation.

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Step 3.2.1

Subtract $3$ from both sides of the equation.

$x = 9 - 3$

Step 3.2.2

Subtract $3$ from $9$ .

$x = 6$

Step 3.3

Next, use the negative value of the $\pm$ to find the second solution.

$x + 3 = - 9$

Step 3.4

Move all terms not containing $x$ to the right side of the equation.

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Step 3.4.1

Subtract $3$ from both sides of the equation.

$x = - 9 - 3$

Step 3.4.2

Subtract $3$ from $- 9$ .

$x = - 12$

Step 3.5

The complete solution is the result of both the positive and negative portions of the solution.

$x = 6, - 12$