Jambmaths question:
If x +1 is a factor of ${{x}^{3}}+3{{x}^{2}}+mx+4$ find the value of m
Option A:
8
Option B:
6
Option C:
–8
Option D:
–6
Jamb Maths Solution:
$\begin{align} & \text{Let }f(x)={{x}^{3}}+3{{x}^{2}}+mx+4 \\ & \text{If }x+1\text{ is a factor, then } \\ & f(-1)=0 \\ & f(-1)={{(-1)}^{3}}+3{{(-1)}^{2}}+m(-1)+4=0 \\ & -1+3-m+4=0 \\ & m=6 \\\end{align}$
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