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

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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) About Me  (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%28+200%2C+200%2C+-6%2C+5%2C+-6%2C+5%2C+y+=+x%2F7+-3%2C+y+=+-7x+%2B7%29+ (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(475) About Me  (Show Source):
You can put this solution on YOUR website!
Solve each equation so that they are in the form y=mx+b
L1 : +x+%96+7y+=+21+
-7y+=+-x+%2B+21+
+y+=+%281%2F7%29x+-+3+
m = 1/7

L2 : +7x+%2B+y+=+7+
+y+=+-7x+%2B7+
m=-7

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