Solve for h 3h^2=h^2+18

$3 h^{2} = h^{2} + 18$

Move all terms containing $h$ to the left side of the equation.

Subtract $h^{2}$ from both sides of the equation.

$3 h^{2} - h^{2} = 18$

Subtract $h^{2}$ from $3 h^{2}$ .

$2 h^{2} = 18$

Divide each term in $2 h^{2} = 18$ by $2$ and simplify.

Divide each term in $2 h^{2} = 18$ by $2$ .

$\frac{2 h^{2}}{2} = \frac{18}{2}$

Simplify the left side.

Cancel the common factor of $2$ .

Cancel the common factor.

$\frac{2 h^{2}}{2} = \frac{18}{2}$

Divide $h^{2}$ by $1$ .

$h^{2} = \frac{18}{2}$

Simplify the right side.

Divide $18$ by $2$ .

$h^{2} = 9$

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

$h = \pm \sqrt{9}$

Simplify $\pm \sqrt{9}$ .

Rewrite $9$ as $3^{2}$ .

$h = \pm \sqrt{3^{2}}$

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

$h = \pm 3$

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.

$h = 3$

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

$h = - 3$

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

$h = 3, - 3$