Solve 20-5s^2=0

$$20 - 5 s ^ { 2 } = 0$$

Solve for s

$$s=2$$

$$s=-2$$

Steps by Finding Square Root

Subtract 20 from both sides. Anything subtracted from zero gives its negation.

$$-5s^{2}=-20$$

Divide both sides by -5.

$$s^{2}=\frac{-20}{-5}$$

Divide -20 by -5 to get 4.

$$s^{2}=4$$

Take the square root of both sides of the equation.

$$s=2 s=-2$$

Steps Using the Quadratic Formula

Quadratic equations like this one, with an x^{2} term but no x term, can still be solved using the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}, once they are put in standard form: ax^{2}+bx+c=0.

$$-5s^{2}+20=0$$

This equation is in standard form: ax^{2}+bx+c=0. Substitute -5 for a, 0 for b, and 20 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$s=\frac{0±\sqrt{0^{2}-4\left(-5\right)\times 20}}{2\left(-5\right)}$$

Square 0.

$$s=\frac{0±\sqrt{-4\left(-5\right)\times 20}}{2\left(-5\right)}$$

Multiply -4 times -5.

$$s=\frac{0±\sqrt{20\times 20}}{2\left(-5\right)}$$

Multiply 20 times 20.

$$s=\frac{0±\sqrt{400}}{2\left(-5\right)}$$

Take the square root of 400.

$$s=\frac{0±20}{2\left(-5\right)}$$

Multiply 2 times -5.

$$s=\frac{0±20}{-10}$$

Now solve the equation s=\frac{0±20}{-10} when ± is plus. Divide 20 by -10.

$$s=-2$$

Now solve the equation s=\frac{0±20}{-10} when ± is minus. Divide -20 by -10.

$$s=2$$

The equation is now solved.

$$s=-2 s=2$$