Solve 4-25x^2=0

$$4-25 { x }^{ 2 } =0$$

Solve for x

$$x=\frac{2}{5}=0.4$$

$$x=-\frac{2}{5}=-0.4$$

Steps by Finding Square Root

Subtract 4 from both sides. Anything subtracted from zero gives its negation.

$$-25x^{2}=-4$$

Divide both sides by -25.

$$x^{2}=\frac{-4}{-25}$$

Fraction \frac{-4}{-25} can be simplified to \frac{4}{25} by removing the negative sign from both the numerator and the denominator.

$$x^{2}=\frac{4}{25}$$

Take the square root of both sides of the equation.

$$x=\frac{2}{5} x=-\frac{2}{5}$$

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.

$$-25x^{2}+4=0$$

This equation is in standard form: ax^{2}+bx+c=0. Substitute -25 for a, 0 for b, and 4 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$x=\frac{0±\sqrt{0^{2}-4\left(-25\right)\times 4}}{2\left(-25\right)}$$

Square 0.

$$x=\frac{0±\sqrt{-4\left(-25\right)\times 4}}{2\left(-25\right)}$$

Multiply -4 times -25.

$$x=\frac{0±\sqrt{100\times 4}}{2\left(-25\right)}$$

Multiply 100 times 4.

$$x=\frac{0±\sqrt{400}}{2\left(-25\right)}$$

Take the square root of 400.

$$x=\frac{0±20}{2\left(-25\right)}$$

Multiply 2 times -25.

$$x=\frac{0±20}{-50}$$

Now solve the equation x=\frac{0±20}{-50} when ± is plus. Reduce the fraction \frac{20}{-50} to lowest terms by extracting and canceling out 10.

$$x=-\frac{2}{5}$$

Now solve the equation x=\frac{0±20}{-50} when ± is minus. Reduce the fraction \frac{-20}{-50} to lowest terms by extracting and canceling out 10.

$$x=\frac{2}{5}$$

The equation is now solved.

$$x=-\frac{2}{5} x=\frac{2}{5}$$