### Home > A2C > Chapter 3 > Lesson 3.2.3 > Problem3-129

3-129.

Solve by first rewriting the equation as an equivalent equation without the square-root sign. After solving the new equation, answer these questions: Do both answers make the original equation true? Was the equation that led to the two solutions equivalent to the original equation? Why or why not? Homework Help ✎

Square both sides of the equation.

4x2 = 8x + 12

Simplify and solve the resulting equation.

x2 − 2x − 3 = 0

x = 3. But, −1 does not work in the original equation.

Substitute each answer in the original equation. Only one of them will satisfy the equation.

$6=\sqrt{36}$

6 = 6

$-2=\sqrt{4}$

−2 = 2