Solve -9x^2=18

$$-9 { x }^{ 2 } =18$$

Solve for x (complex solution)

$$x=-\sqrt{2}i\approx -0-1.414213562i$$

$$x=\sqrt{2}i\approx 1.414213562i$$

Steps by Finding Square Root

Divide both sides by -9.

$$x^{2}=\frac{18}{-9}$$

Divide 18 by -9 to get -2.

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

The equation is now solved.

$$x=\sqrt{2}i x=-\sqrt{2}i$$

Steps Using the Quadratic Formula

Divide both sides by -9.

$$x^{2}=\frac{18}{-9}$$

Divide 18 by -9 to get -2.

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

Add 2 to both sides.

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

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

$$x=\frac{0±\sqrt{0^{2}-4\times 2}}{2}$$

Square 0.

$$x=\frac{0±\sqrt{-4\times 2}}{2}$$

Multiply -4 times 2.

$$x=\frac{0±\sqrt{-8}}{2}$$

Take the square root of -8.

$$x=\frac{0±2\sqrt{2}i}{2}$$

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

$$x=\sqrt{2}i$$

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

$$x=-\sqrt{2}i$$

The equation is now solved.

$$x=\sqrt{2}i x=-\sqrt{2}i$$