Question:
If $x+1$ is a factor of the polynomial $2 x^{2}+k x$, then the value of $k$ is
(a) $-3$
(b) 4
(c) 2
(d)-2
Solution:
(c) Let p(x) = 2x2 + kx
Since, (x + 1) is a factor of p(x), then
p(-1)=0
2(-1)2 + k(-1) = 0
=> 2-k = 0 => k= 2
Hence, the value of k is 2.