Solve this

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 :

$2 \times(-1)^{2}+k \times(-1)=0$

$\Rightarrow 2-k=0$

$\Rightarrow k=2$