Jambmaths question:
Find the value of k if y – 1 is a factor of ${{y}^{3}}+4{{y}^{2}}+ky-6$
Option A:
–4
Option B:
1
Option C:
0
Option D:
–6
Jamb Maths Solution:
$\begin{align} & \text{let }f(y)={{y}^{3}}+4{{y}^{2}}+ky-6 \\ & \text{since (}y-1)\text{ is a factor, }f(1)=0 \\ & f(1)={{1}^{3}}+4(1)+k(1)-6=0 \\ & 1+4+k-6=0 \\ & k=1 \\\end{align}$
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