Question: If $(x+1)$ is a factor of $\left(2 x^{2}+k x\right)$, then $k=?$
(a) 4
(b) $-3$
(c) 2
(d) $-2$
Solution:
(c) 2.
$(x+1)$ is a factor of $2 x^{2}+k x$
So, $-1$ is a zero of $2 x^{2}+k x$.
Thus, we have :
$2 \times(-1)^{2}+k \times(-1)=0$
$\Rightarrow 2-k=0$
$\Rightarrow k=2$