Solve Using the Square Root Property x^2=400

$x^{2} = 400$

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

$x = \pm \sqrt{400}$

Simplify $\pm \sqrt{400}$ .

Rewrite $400$ as $20^{2}$ .

$x = \pm \sqrt{20^{2}}$

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

$x = \pm 20$

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

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

$x = 20$

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

$x = - 20$

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

$x = 20, - 20$