Solve for r r^2-4=0

$r^{2} - 4 = 0$

Step 1

Add $4$ to both sides of the equation.

$r^{2} = 4$

Step 2

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

$r = \pm \sqrt{4}$

Step 3

Simplify $\pm \sqrt{4}$ .

Rewrite $4$ as $2^{2}$ .

$r = \pm \sqrt{2^{2}}$

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

$r = \pm 2$

Step 4

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.

$r = 2$

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

$r = - 2$

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

$r = 2, - 2$