Question:
Find the value of a so that the point (3, a) lies on the line represented by 2x − 3y + 5 = 0
Solution:
If a point $\left(x_{1}, y_{1}\right)$ is said lie on a line represented by $a x+b y+c=0$, then the given equation of the line should hold true when the values of the co-ordinates of the points are substituted in it.
Here it is said that the point $(3, a)$ lies on the line represented by the equation $2 x-3 y+5=0$.
Substituting the co-ordinates of the values in the equation of the line we have,
$2 x-3 y+5=0$
$2(3)-3(a)+5=0$
$3 a=6+5$
$3 a=11$
$a=\frac{11}{3}$
Thus the value of ' $a$ ' satisfying the given conditions is $a=\frac{11}{3}$.