Consider the lines Let's say that a pair of lines is
y=3x+52y=4x+53y=9x−22y=x−34y=x−5.
if the two lines are either parallel or perpendicular to each other. Among all the pairs of lines shown, how many pairs are good?
(1) y = 3x + 5 ......slope = 3
(2) 2y = 4x + 5 .......slope = 2
(3) 3y = 9x - 2 .........slope = 3
94) 2y = x - 3 ........slope = 1/2
(5) 4y = x - 5 .......slope = 1/4
Only one pair is parallel (1) and (3)
+42 
