SOLUTION: Are the following lines parallel, perpendicular, or neither? L1 with equation x � 7y = 21 L2 with equation 7x + y = 7 A) Parallel B) Perpendicular C) Neither

Question 74540: Are the following lines parallel, perpendicular, or neither?
L1 with equation x � 7y = 21
L2 with equation 7x + y = 7
A) Parallel
B) Perpendicular
C) Neither

Found 2 solutions by checkley75, Cintchr:
Answer by checkley75(3666) (Show Source): You can put this solution on YOUR website!
X-7Y=21, -7Y=-X+21, Y=-X/-7+21/-7, Y=X/7-3
7X+Y=7, Y=-7X+7
(graph 200x200 pixels, x from -6 to 5, y from -6 to 5, of TWO functions y = x/7 -3 and y = -7x +7).
they look perpendicular to me AND the slopes are negative recipricals of each other. (definition of parallel lines).
Answer by Cintchr(481) (Show Source): You can put this solution on YOUR website!
Solve each equation so that they are in the form y=mx+b
L1 :

m = 1/7

L2 :

m=-7

since the slopes are opposite reciprocals of one another, the lines are perpendicular to one another.
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