Solve a^2=729

$$a ^ { 2 } = 729$$

Solve for a

$$a=27$$

$$a=-27$$

Steps Using Difference of Squares

Subtract 729 from both sides.

$$a^{2}-729=0$$

Consider a^{2}-729. Rewrite a^{2}-729 as a^{2}-27^{2}. The difference of squares can be factored using the rule: a^{2}-b^{2}=\left(a-b\right)\left(a+b\right).

$$\left(a-27\right)\left(a+27\right)=0$$

To find equation solutions, solve a-27=0 and a+27=0.

$$a=27 a=-27$$

Steps by Finding Square Root

Take the square root of both sides of the equation.

$$a=27 a=-27$$

Steps Using the Quadratic Formula

Subtract 729 from both sides.

$$a^{2}-729=0$$

This equation is in standard form: ax^{2}+bx+c=0. Substitute 1 for a, 0 for b, and -729 for c in the quadratic formula, \frac{-b±\sqrt{b^{2}-4ac}}{2a}.

$$a=\frac{0±\sqrt{0^{2}-4\left(-729\right)}}{2}$$

Square 0.

$$a=\frac{0±\sqrt{-4\left(-729\right)}}{2}$$

Multiply -4 times -729.

$$a=\frac{0±\sqrt{2916}}{2}$$

Take the square root of 2916.

$$a=\frac{0±54}{2}$$

Now solve the equation a=\frac{0±54}{2} when ± is plus. Divide 54 by 2.

$$a=27$$

Now solve the equation a=\frac{0±54}{2} when ± is minus. Divide -54 by 2.

$$a=-27$$

The equation is now solved.

$$a=27 a=-27$$