Solve b^2-6=72

$$b ^ { 2 } - 6 = 72$$

Solve for b

$$b=\sqrt{78}\approx 8.831760866$$

$$b=-\sqrt{78}\approx -8.831760866$$

Steps by Finding Square Root

Add 6 to both sides.

$$b^{2}=72+6$$

Add 72 and 6 to get 78.

$$b^{2}=78$$

Take the square root of both sides of the equation.

$$b=\sqrt{78} b=-\sqrt{78}$$

Steps Using the Quadratic Formula

Subtract 72 from both sides.

$$b^{2}-6-72=0$$

Subtract 72 from -6 to get -78.

$$b^{2}-78=0$$

This equation is in standard form: ax^{2}+bx+c=0. Substitute 1 for a, 0 for b, and -78 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

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

Square 0.

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

Multiply -4 times -78.

$$b=\frac{0±\sqrt{312}}{2}$$

Take the square root of 312.

$$b=\frac{0±2\sqrt{78}}{2}$$

Now solve the equation b=\frac{0±2\sqrt{78}}{2} when ± is plus.

$$b=\sqrt{78}$$

Now solve the equation b=\frac{0±2\sqrt{78}}{2} when ± is minus.

$$b=-\sqrt{78}$$

The equation is now solved.

$$b=\sqrt{78} b=-\sqrt{78}$$