Question 583566
Determine whether the lines are parallel, perpendicular or neither.  There is a discrepancy three of us are having! lol)   
3x + 6y =21
-6x + 3y = 9
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Solve for y
3x + 6y =21
y = (-1/2)x + 7/2
Slope m1 = -1/2
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-6x + 3y = 9
y = 2x + 3
Slope m2 = 2
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m1*m2 = -1 --> perpendicular
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If the slopes are negative inverses --> perpendicular
If the slopes are equal --> parallel