SOLUTION: Are the following lines parallel, perpendicular or neither? L1 with equation x-3y =9 L2 with equation 3x+y=3 I used the formula y=mx+b but I don't know if that's right. 9

Algebra ->  Linear-equations -> SOLUTION: Are the following lines parallel, perpendicular or neither? L1 with equation x-3y =9 L2 with equation 3x+y=3 I used the formula y=mx+b but I don't know if that's right. 9      Log On


   

Question 106646: Are the following lines parallel, perpendicular or neither?
L1 with equation x-3y =9
L2 with equation 3x+y=3

I used the formula y=mx+b but I don't know if that's right.
9= x - 3y
3 = x-y


3 = 3x+y
1=x + y
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Are the following lines parallel, perpendicular or neither?
L1 with equation x-3y =9
L2 with equation 3x+y=3
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L1: 3y=x-9
y=(1/3)x-3
slope is 1/3
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L2: y = -3x+3
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slope is -3
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Since (1/3)(-3)= -1 the lines are perpendicular.
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Cheers,
Stan H>