Solve 7xleft(8*xright)=28

$$7x \left( 8 \times x \right) = 28$$

Solve for x

$$x=\frac{\sqrt{2}}{2}\approx 0.707106781$$

$$x=-\frac{\sqrt{2}}{2}\approx -0.707106781$$

Steps by Finding Square Root

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

$$7x^{2}\times 8=28$$

Multiply 7 and 8 to get 56.

$$56x^{2}=28$$

Divide both sides by 56.

$$x^{2}=\frac{28}{56}$$

Reduce the fraction \frac{28}{56} to lowest terms by extracting and canceling out 28.

$$x^{2}=\frac{1}{2}$$

Take the square root of both sides of the equation.

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

Steps Using the Quadratic Formula

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

$$7x^{2}\times 8=28$$

Multiply 7 and 8 to get 56.

$$56x^{2}=28$$

Subtract 28 from both sides.

$$56x^{2}-28=0$$

This equation is in standard form: ax^{2}+bx+c=0. Substitute 56 for a, 0 for b, and -28 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$x=\frac{0±\sqrt{0^{2}-4\times 56\left(-28\right)}}{2\times 56}$$

Square 0.

$$x=\frac{0±\sqrt{-4\times 56\left(-28\right)}}{2\times 56}$$

Multiply -4 times 56.

$$x=\frac{0±\sqrt{-224\left(-28\right)}}{2\times 56}$$

Multiply -224 times -28.

$$x=\frac{0±\sqrt{6272}}{2\times 56}$$

Take the square root of 6272.

$$x=\frac{0±56\sqrt{2}}{2\times 56}$$

Multiply 2 times 56.

$$x=\frac{0±56\sqrt{2}}{112}$$

Now solve the equation x=\frac{0±56\sqrt{2}}{112} when ± is plus.

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

Now solve the equation x=\frac{0±56\sqrt{2}}{112} when ± is minus.

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

The equation is now solved.

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