Chapter 9 - Quadratic Functions and Equations - 9-3 Solving Quadratic Equations - Practice and Problem-Solving Exercises - Page 551: 9

$$x = \pm2$$

First add 12 on both sides $$3x^2 = 12$$ Then divide by 3 on both sides $$x^2 = 4$$ Then you should find the square root of both sides $$x = \pm2$$ Remember the square root of any number above 0 has 2 answers.