Question

If roots of the quadratic equation $3y^2+ky+12=0$ are real and equal, then find k.

• A. $12$
• B. $-12$
• C. $\pm 12$
• D. $\pm 13$

Answer 1

The correct option is C $\pm 12$

$$\begin{array}{c}3y^2+ky+12\\ b^2-4ac=0\\ K^2-144=0\\ K=\pm \sqrt{144}\\ k=\pm 12\end{array}$$