Question 81538: Determine which two equations represent perpendicular lines.
y=5/8x-3
y=3x-5/8
y=-1/3x+5/8
y=1/3x-
Answer by tutor_paul(519)   (Show Source):
You can put this solution on YOUR website! To do this problem you need to know understand 2 concepts:
#1 How do I a get the slope of a line from it's equation?
#2 What is the relationship of the slopes of 2 lines that are perpendicular?
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For concept #1, you can get the slope of a line from it's equation easily once the equation is in slope/intercept form. Slope/intercept form is:
When the equation is in this form, the 'm' term is the slope. It is that simple!
As it turns out, ALL of the equations given in your problem are in slope/intercept form, so you can read off the slope of each one quite easily. For example, in the first equation, the slope is 5/8, in the second one, it is 3, etc.
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For concept #2, you just need to recognize that perpendicular lines have slopes which are negative reciprocals of each other. To determine the negative reciprocal of something, divide it into 1 and change the sign. For example, the negative reciprocal of -2 is 1/2. The negative reciprocal of 2/3 is -3/2.
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So, now that you know these 2 concepts, the problem becomes easy. Which slopes of the lines given are negative reciprocals of each other? If you can't figure that out from the information given, send me an email.
good Luck,
tutor_paul@yahoo.com
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