Question

determine whethe the given linear equations are parallel, perpendicular, or neither : y = 9x - 8 and y = -9x +11

Answer 1

These equations are in slope-intercept form \[(y=mx+b)\] which implies that the coefficient of x in each equation is the slope if that equation. Hence the first line has slope 9 and the second has slope -9.

Also, recall that two lines are parallel if and only if they have the same slope, and perpendicular if and only if the product of their slopes is -1. Obviously the numbers 9 and -9 do not satisfy either of there conditions; therefore, the linear equations are neither parallel nor perpendicular.

Answer 2

to be perpendicular m*m'=-1, so neither

Answer 3

parallel m=m' and h neq h'

Answer 4

Thank you Raphael, I stand corrected. Two lines are parallel if and only if they have the same slope AND DIFFERENT Y-INTERCEPTS. :)