Jambmaths question:
Use the graph above to find the value if $px+qy\le 4$
Option A:
p = 2, q = 1
Option B:
p = 2, q = –1
Option C:
p = 1, q = 2
Option D:
p = –1 , q = 2
Jamb Maths Solution:
$\begin{align} & \text{The given coordinate are }({{x}_{1}},{{y}_{1}})=(-4,0) \\ & \text{ }({{x}_{2}},{{y}_{2}})=(0,2) \\ & \text{Using the two point form equation } \\ & \frac{y-{{y}_{1}}}{x-{{x}_{1}}}=\frac{{{y}_{2}}-{{y}_{1}}}{{{x}_{2}}-{{x}_{1}}} \\ & \frac{y-0}{x-(-4)}=\frac{2-0}{0-(-4)} \\ & \frac{y}{x+4}=\frac{2}{4} \\ & \frac{y}{x+4}=\frac{1}{2} \\ & 2y=x+4 \\ & -x+2y=4 \\ & \text{Introducing the inquality sign} \\ & -x+2y\le 4 \\ & \text{Comparing the two equation } \\ & -x+2y\le 4\text{ and }px+qy\le 4 \\ & \text{shows that }p=-1,\text{ }q=2 \\ & (p,q)=(-1,2) \\\end{align}$
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