# Which of the following is a solution to the equation 5x^2-12=168? A. 6.75 B.-6 C.5 D.-5.59

## This question has really stumped me

B. $x = - 6$
We are given that $5 {x}^{2} - 12 = 168$. Adding $12$ to both sides yields $5 {x}^{2} = 180$. Dividing $5$ from both sides gives ${x}^{2} = 36$.
We can now take the square root of both sides, making sure to add a $\pm$ next to our radical. This gives $x = \pm \sqrt{36} = \pm 6$.
Thus, our solutions are $x = 6$ and $x = - 6$. The latter solution corresponds to choice (B).