Solve 2x(x-2)=6

$$2 x ( x - 2 ) = 6$$

Solve for x

$$x=-1$$

$$x=3$$

Steps Using the Quadratic Formula

Use the distributive property to multiply 2x by x-2.

$$2x^{2}-4x=6$$

Subtract 6 from both sides.

$$2x^{2}-4x-6=0$$

This equation is in standard form: ax^{2}+bx+c=0. Substitute 2 for a, -4 for b, and -6 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$x=\frac{-\left(-4\right)±\sqrt{\left(-4\right)^{2}-4\times 2\left(-6\right)}}{2\times 2}$$

Square -4.

$$x=\frac{-\left(-4\right)±\sqrt{16-4\times 2\left(-6\right)}}{2\times 2}$$

Multiply -4 times 2.

$$x=\frac{-\left(-4\right)±\sqrt{16-8\left(-6\right)}}{2\times 2}$$

Multiply -8 times -6.

$$x=\frac{-\left(-4\right)±\sqrt{16+48}}{2\times 2}$$

Add 16 to 48.

$$x=\frac{-\left(-4\right)±\sqrt{64}}{2\times 2}$$

Take the square root of 64.

$$x=\frac{-\left(-4\right)±8}{2\times 2}$$

The opposite of -4 is 4.

$$x=\frac{4±8}{2\times 2}$$

Multiply 2 times 2.

$$x=\frac{4±8}{4}$$

Now solve the equation x=\frac{4±8}{4} when ± is plus. Add 4 to 8.

$$x=\frac{12}{4}$$

Divide 12 by 4.

$$x=3$$

Now solve the equation x=\frac{4±8}{4} when ± is minus. Subtract 8 from 4.

$$x=-\frac{4}{4}$$

Divide -4 by 4.

$$x=-1$$

The equation is now solved.

$$x=3 x=-1$$

Steps for Completing the Square

Use the distributive property to multiply 2x by x-2.

$$2x^{2}-4x=6$$

Divide both sides by 2.

$$\frac{2x^{2}-4x}{2}=\frac{6}{2}$$

Dividing by 2 undoes the multiplication by 2.

$$x^{2}+\left(-\frac{4}{2}\right)x=\frac{6}{2}$$

Divide -4 by 2.

$$x^{2}-2x=\frac{6}{2}$$

Divide 6 by 2.

$$x^{2}-2x=3$$

Divide -2, the coefficient of the x term, by 2 to get -1. Then add the square of -1 to both sides of the equation. This step makes the left hand side of the equation a perfect square.

$$x^{2}-2x+1=3+1$$

Add 3 to 1.

$$x^{2}-2x+1=4$$

Factor x^{2}-2x+1. In general, when x^{2}+bx+c is a perfect square, it can always be factored as \left(x+\frac{b}{2}\right)^{2}.

$$\left(x-1\right)^{2}=4$$

Take the square root of both sides of the equation.

$$\sqrt{\left(x-1\right)^{2}}=\sqrt{4}$$

Simplify.

$$x-1=2 x-1=-2$$

Add 1 to both sides of the equation.

$$x=3 x=-1$$