Solve 2x*x=42

$$2x \times x=42$$

Solve for x

$$x=\sqrt{21}\approx 4.582575695$$

$$x=-\sqrt{21}\approx -4.582575695$$

Steps by Finding Square Root

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

$$2x^{2}=42$$

Divide both sides by 2.

$$x^{2}=\frac{42}{2}$$

Divide 42 by 2 to get 21.

$$x^{2}=21$$

Take the square root of both sides of the equation.

$$x=\sqrt{21} x=-\sqrt{21}$$

Steps Using the Quadratic Formula

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

$$2x^{2}=42$$

Subtract 42 from both sides.

$$2x^{2}-42=0$$

This equation is in standard form: ax^{2}+bx+c=0. Substitute 2 for a, 0 for b, and -42 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$x=\frac{0±\sqrt{0^{2}-4\times 2\left(-42\right)}}{2\times 2}$$

Square 0.

$$x=\frac{0±\sqrt{-4\times 2\left(-42\right)}}{2\times 2}$$

Multiply -4 times 2.

$$x=\frac{0±\sqrt{-8\left(-42\right)}}{2\times 2}$$

Multiply -8 times -42.

$$x=\frac{0±\sqrt{336}}{2\times 2}$$

Take the square root of 336.

$$x=\frac{0±4\sqrt{21}}{2\times 2}$$

Multiply 2 times 2.

$$x=\frac{0±4\sqrt{21}}{4}$$

Now solve the equation x=\frac{0±4\sqrt{21}}{4} when ± is plus.

$$x=\sqrt{21}$$

Now solve the equation x=\frac{0±4\sqrt{21}}{4} when ± is minus.

$$x=-\sqrt{21}$$

The equation is now solved.

$$x=\sqrt{21} x=-\sqrt{21}$$