Question 106646
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>