Solve 81.2=x(x)

$$81.2 = x ( x )$$

Solve for x

$$x = \frac{\sqrt{2030}}{5} \approx 9.011104261$$

$$x = -\frac{\sqrt{2030}}{5} \approx -9.011104261$$

Steps by Finding Square Root

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

$$81.2=x^{2}$$

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

$$x^{2}=81.2$$

Take the square root of both sides of the equation.

$$x=\frac{\sqrt{2030}}{5} x=-\frac{\sqrt{2030}}{5}$$

Steps Using the Quadratic Formula

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

$$81.2=x^{2}$$

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

$$x^{2}=81.2$$

Subtract 81.2 from both sides.

$$x^{2}-81.2=0$$

This equation is in standard form: ax^{2}+bx+c=0. Substitute 1 for a, 0 for b, and -81.2 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$x=\frac{0±\sqrt{0^{2}-4\left(-81.2\right)}}{2}$$

Square 0.

$$x=\frac{0±\sqrt{-4\left(-81.2\right)}}{2}$$

Multiply -4 times -81.2.

$$x=\frac{0±\sqrt{324.8}}{2}$$

Take the square root of 324.8.

$$x=\frac{0±\frac{2\sqrt{2030}}{5}}{2}$$

Now solve the equation x=\frac{0±\frac{2\sqrt{2030}}{5}}{2} when ± is plus.

$$x=\frac{\sqrt{2030}}{5}$$

Now solve the equation x=\frac{0±\frac{2\sqrt{2030}}{5}}{2} when ± is minus.

$$x=-\frac{\sqrt{2030}}{5}$$

The equation is now solved.

$$x=\frac{\sqrt{2030}}{5} x=-\frac{\sqrt{2030}}{5}$$