Solve 3*x*x=78

$$3 \times x \times x = 78$$

Solve for x

$$x=\sqrt{26}\approx 5.099019514$$

$$x=-\sqrt{26}\approx -5.099019514$$

Steps by Finding Square Root

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

$$3x^{2}=78$$

Divide both sides by 3.

$$x^{2}=\frac{78}{3}$$

Divide 78 by 3 to get 26.

$$x^{2}=26$$

Take the square root of both sides of the equation.

$$x=\sqrt{26} x=-\sqrt{26}$$

Steps Using the Quadratic Formula

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

$$3x^{2}=78$$

Subtract 78 from both sides.

$$3x^{2}-78=0$$

This equation is in standard form: ax^{2}+bx+c=0. Substitute 3 for a, 0 for b, and -78 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$x=\frac{0±\sqrt{0^{2}-4\times 3\left(-78\right)}}{2\times 3}$$

Square 0.

$$x=\frac{0±\sqrt{-4\times 3\left(-78\right)}}{2\times 3}$$

Multiply -4 times 3.

$$x=\frac{0±\sqrt{-12\left(-78\right)}}{2\times 3}$$

Multiply -12 times -78.

$$x=\frac{0±\sqrt{936}}{2\times 3}$$

Take the square root of 936.

$$x=\frac{0±6\sqrt{26}}{2\times 3}$$

Multiply 2 times 3.

$$x=\frac{0±6\sqrt{26}}{6}$$

Now solve the equation x=\frac{0±6\sqrt{26}}{6} when ± is plus.

$$x=\sqrt{26}$$

Now solve the equation x=\frac{0±6\sqrt{26}}{6} when ± is minus.

$$x=-\sqrt{26}$$

The equation is now solved.

$$x=\sqrt{26} x=-\sqrt{26}$$