Is the line x – 3y = 4 perpendicular to the line 3x – y = 7?

Given lines, ⇒ x - 3y = 4 and 3x - y = 7 ⇒ 3y = x - 4 and y = 3x - 7 ⇒ y = and y = 3x - 7 Comparing above equations with y = mx + c we get, Slope of 1st line = Slope of 2nd line = 3 Since, Slope of 1st line × Slope of 2nd line = which is not equal to -1. Hence, the lines x - 3y = 4 and 3x - y = 7 are not perpendicular to each other.