Example Find the slope of the graph y = -3x + 1 using coordinates.

Solution : y = -3x + 1, put x = 1, then y = -3(1) + 1 = -2

Let A(1, -2)

and put x = -1 then y = -3 (-1) +1 = 4

Let B (-1, 4)

Pick these two points A(1,-2) and B(-1,4) and calculate the slope 'm'

Example Are the two lines y + x = 2 and y = x + 4 parallel?

Solution : y + x = 2 put x = 1 then y = 1. Let A(1,1)

put x = -1 then y = 3. Let B (-1, 3)

Therefore, the slope of line AB i.e. y + x = 2 is

Also y = x + 4 put x =1 then y = 5 Let C (1,5) and

put x = -1 then y = 3 Let D (-1,3)

Therefore, slope of line CD i.e. y = x + 4 is

Since the two slopes m₁ and m₂ are not equal the two lines are not parallel to each other.

Index

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

Chapter 9