Ans: C
The quadratic equation has equal roots, then $\Delta=0$.
The quadratic equation has equal roots, then $\Delta=0$.
$\begin{array}{rcl}
(2k)^2-4(3)(-k) & = & 0 \\
4k^2+12k & = & 0 \\
k(k+3) & = & 0
\end{array}$
Therefore, $k=0$ or $k=-3$.
