Solve x^2+2=81

$${ x }^{ 2 } +2=81$$

Solve for x

$$x=\sqrt{79}\approx 8.888194417$$

$$x=-\sqrt{79}\approx -8.888194417$$

Steps by Finding Square Root

Subtract 2 from both sides.

$$x^{2}=81-2$$

Subtract 2 from 81 to get 79.

$$x^{2}=79$$

Take the square root of both sides of the equation.

$$x=\sqrt{79} x=-\sqrt{79}$$

Steps Using the Quadratic Formula

Subtract 81 from both sides.

$$x^{2}+2-81=0$$

Subtract 81 from 2 to get -79.

$$x^{2}-79=0$$

This equation is in standard form: ax^{2}+bx+c=0. Substitute 1 for a, 0 for b, and -79 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$x=\frac{0±\sqrt{0^{2}-4\left(-79\right)}}{2}$$

Square 0.

$$x=\frac{0±\sqrt{-4\left(-79\right)}}{2}$$

Multiply -4 times -79.

$$x=\frac{0±\sqrt{316}}{2}$$

Take the square root of 316.

$$x=\frac{0±2\sqrt{79}}{2}$$

Now solve the equation x=\frac{0±2\sqrt{79}}{2} when ± is plus.

$$x=\sqrt{79}$$

Now solve the equation x=\frac{0±2\sqrt{79}}{2} when ± is minus.

$$x=-\sqrt{79}$$

The equation is now solved.

$$x=\sqrt{79} x=-\sqrt{79}$$