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rdaniel20r423
determine whethe the given linear equations are parallel, perpendicular, or neither : y = 9x - 8 and y = -9x +11
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.
to be perpendicular m*m'=-1, so neither
parallel m=m' and h neq h'
Thank you Raphael, I stand corrected. Two lines are parallel if and only if they have the same slope AND DIFFERENT Y-INTERCEPTS. :)