Question

If $(x+1)$ is a factor of $3x^2+kx+4=0$, then $k=$

• A. $3$
• B. $6$
• C. $-7$
• D. $7$

Answer 1

The correct option is D $7$

Given, $x+1$ is factor of $f\left(x\right)={3x}^2+kx+4$

$\Rightarrow f(-1)=0$

$\Rightarrow 3{(-1)}^2+k(-1)+4=0$

$\Rightarrow -k+7=0\Rightarrow k=7$ [D]