Jambmaths question:
The shaded area in the diagram above is represented by
Option A:
${(x,y):y-3x<-6}$
Option B:
${(x,y):y+3x<6}$
Option C:
${(x,y):y+3x<-6}$
Option D:
${(x,y):y-3x<6}$
Jamb Maths Solution:
$\begin{align} & ({{x}_{1}},{{y}_{1}})=(2,0) \\ & ({{x}_{2}},{{y}_{2}})=(0,4) \\ & \text{Equation of the line using two point equation} \\ & \frac{y-{{y}_{1}}}{x-{{x}_{1}}}=\frac{{{y}_{2}}-{{y}_{1}}}{{{x}_{2}}-{{x}_{1}}} \\ & \frac{y-0}{x-2}=\frac{6-0}{0-2} \\ & \frac{y}{x-2}=\frac{6}{-2} \\ & \frac{y}{x-2}=-3 \\ & y=-3x+6 \\ & y+3x=6 \\ & \text{Looking at the graph},\text{ and the portion that is shaded} \\ & \text{Option B is the correct option},\text{ test this yourself} \\\end{align}$
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