Solve 216=x*x

$$216 = x \times x$$

Solve for x

$$x=6\sqrt{6}\approx 14.696938457$$

$$x=-6\sqrt{6}\approx -14.696938457$$

Steps by Finding Square Root

Multiply x and x to get x^{2}.

$$216=x^{2}$$

Swap sides so that all variable terms are on the left hand side.

$$x^{2}=216$$

Take the square root of both sides of the equation.

$$x=6\sqrt{6} x=-6\sqrt{6}$$

Steps Using the Quadratic Formula

Multiply x and x to get x^{2}.

$$216=x^{2}$$

Swap sides so that all variable terms are on the left hand side.

$$x^{2}=216$$

Subtract 216 from both sides.

$$x^{2}-216=0$$

This equation is in standard form: ax^{2}+bx+c=0. Substitute 1 for a, 0 for b, and -216 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$x=\frac{0±\sqrt{0^{2}-4\left(-216\right)}}{2}$$

Square 0.

$$x=\frac{0±\sqrt{-4\left(-216\right)}}{2}$$

Multiply -4 times -216.

$$x=\frac{0±\sqrt{864}}{2}$$

Take the square root of 864.

$$x=\frac{0±12\sqrt{6}}{2}$$

Now solve the equation x=\frac{0±12\sqrt{6}}{2} when ± is plus.

$$x=6\sqrt{6}$$

Now solve the equation x=\frac{0±12\sqrt{6}}{2} when ± is minus.

$$x=-6\sqrt{6}$$

The equation is now solved.

$$x=6\sqrt{6} x=-6\sqrt{6}$$