Question

The roots of the following quadratic equation is real and equal, find k.

3y² + ky +12 = 0

Answer 1

 3y² + ky +12 = 0
The roots of the given quadratic equation are real and equal. So, the discriminant will be 0.

\[b^2 - 4ac = 0\]
\[ \Rightarrow k^2 - 4 \times 3 \times 12 = 0\]
\[ \Rightarrow k^2 - 144 = 0\]
\[ \Rightarrow k^2 = 144\]
\[ \Rightarrow k = \pm 12\]