Question:
Draw the graph of the equation 2x − 3y = 5. From the graph, find (i) the value of y when x = 4 and (ii) the value of x when y = 3.
Solution:
Given equation :
$2 x-3 y=5$
$\Rightarrow 2 x=3 y+5$
$\Rightarrow x=\frac{3 y+5}{2}$
When, $y=-1, x=\frac{-3+5}{2}=\frac{2}{2}=1$
When, $y=-3, x=\frac{-9+5}{2}=\frac{-4}{2}=-2$
Thus, we have the following table:
Plot the points $(-2,-3),(1,-1)$ on the graph paper and extend the line in both directions.
(i) When x = 4:
$4=\frac{3 y+5}{2} \Rightarrow 8=3 y+5$
$\Rightarrow 3 y=8-5=3$
$\Rightarrow 3 y=3$
$\Rightarrow y=1$
(ii) When y = 3:
$x=\frac{3 y+5}{2}=\frac{14}{2}=7$