Solve 2xx+9=18

$$2xx+9 = 18$$

Solve for x

$$x = \frac{3 \sqrt{2}}{2} \approx 2.121320344$$

$$x = -\frac{3 \sqrt{2}}{2} \approx -2.121320344$$

Steps by Finding Square Root

Multiply x and x to get x^{2}.

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

Subtract 9 from both sides.

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

Subtract 9 from 18 to get 9.

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

Divide both sides by 2.

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

Take the square root of both sides of the equation.

$$x=\frac{3\sqrt{2}}{2} x=-\frac{3\sqrt{2}}{2}$$

Steps Using the Quadratic Formula

Multiply x and x to get x^{2}.

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

Subtract 18 from both sides.

$$2x^{2}+9-18=0$$

Subtract 18 from 9 to get -9.

$$2x^{2}-9=0$$

This equation is in standard form: ax^{2}+bx+c=0. Substitute 2 for a, 0 for b, and -9 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$x=\frac{0±\sqrt{0^{2}-4\times 2\left(-9\right)}}{2\times 2}$$

Square 0.

$$x=\frac{0±\sqrt{-4\times 2\left(-9\right)}}{2\times 2}$$

Multiply -4 times 2.

$$x=\frac{0±\sqrt{-8\left(-9\right)}}{2\times 2}$$

Multiply -8 times -9.

$$x=\frac{0±\sqrt{72}}{2\times 2}$$

Take the square root of 72.

$$x=\frac{0±6\sqrt{2}}{2\times 2}$$

Multiply 2 times 2.

$$x=\frac{0±6\sqrt{2}}{4}$$

Now solve the equation x=\frac{0±6\sqrt{2}}{4} when ± is plus.

$$x=\frac{3\sqrt{2}}{2}$$

Now solve the equation x=\frac{0±6\sqrt{2}}{4} when ± is minus.

$$x=-\frac{3\sqrt{2}}{2}$$

The equation is now solved.

$$x=\frac{3\sqrt{2}}{2} x=-\frac{3\sqrt{2}}{2}$$