Example Find p and q if the points A (3, 0) and B(2, - 4/3) lie on the graph of px + qy = 12.

Solution : Since A (3, 0) lies on the line px + qy = 12

We have, p (3) + q (0) = 12 i.e. 3p = 12 \ p = 4

Also B (2, - 4/3) lies on the line px + qy = 12

We have, p (2) + q (-4/3) = 12 i.e.

Inserting p = 4 we get,

Example Find the equation of the straight line, perpendicular to 3x + 5y + 3 = 0 and through (2, -1).

Solution : 3x + 5y + 3 = 0

\ Its slope (m1) =

Let the slope of the line perpendicular to it be m₂

then m₂ =

It passes through (2, -1)

\ The equation of the required line will be

Index

8.1 Definition
8.2 Relations, Graphs and Symmetry
8.3 Slopes and Intercepts

Chapter 9