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 m_{1} and m_{2} are not equal the two lines are not parallel to each other.
