Solve -3x^2+20=8

$$- 3 x ^ { 2 } + 20 = 8$$

Solve for x

$$x=2$$

$$x=-2$$

Steps by Finding Square Root

Subtract 20 from both sides.

$$-3x^{2}=8-20$$

Subtract 20 from 8 to get -12.

$$-3x^{2}=-12$$

Divide both sides by -3.

$$x^{2}=\frac{-12}{-3}$$

Divide -12 by -3 to get 4.

$$x^{2}=4$$

Take the square root of both sides of the equation.

$$x=2 x=-2$$

Steps Using the Quadratic Formula

Subtract 8 from both sides.

$$-3x^{2}+20-8=0$$

Subtract 8 from 20 to get 12.

$$-3x^{2}+12=0$$

This equation is in standard form: ax^{2}+bx+c=0. Substitute -3 for a, 0 for b, and 12 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$x=\frac{0±\sqrt{0^{2}-4\left(-3\right)\times 12}}{2\left(-3\right)}$$

Square 0.

$$x=\frac{0±\sqrt{-4\left(-3\right)\times 12}}{2\left(-3\right)}$$

Multiply -4 times -3.

$$x=\frac{0±\sqrt{12\times 12}}{2\left(-3\right)}$$

Multiply 12 times 12.

$$x=\frac{0±\sqrt{144}}{2\left(-3\right)}$$

Take the square root of 144.

$$x=\frac{0±12}{2\left(-3\right)}$$

Multiply 2 times -3.

$$x=\frac{0±12}{-6}$$

Now solve the equation x=\frac{0±12}{-6} when ± is plus. Divide 12 by -6.

$$x=-2$$

Now solve the equation x=\frac{0±12}{-6} when ± is minus. Divide -12 by -6.

$$x=2$$

The equation is now solved.

$$x=-2 x=2$$