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Question 249107: I do not understand how to solve for m. I know that this should be y=mx+b
but I cant remember how to do these problems. I have my math final on Monday night and I am really needing help on how to solve these
the question I am showing is "Write an equation of the line that passes through the point (-3,-1) and is perpindicular to the line x + 3y = 9. Can someone help me with this?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Write an equation of the line that passes through the point (-3,-1) and is perpendicular to the line x + 3y = 9.
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Find the slope of the given line:
3y = -x + 9
y = (-1/3)x + 3
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Slope of the given line is -1/3.
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Note: Any line perpendicular to the given line must have slope -3.
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Your Problem:
You want the equation of the line that has slope -3 and passes thru (-3,-1).
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Form of the line is y = mx + b; you need to find "m" and "b":
m = -3
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-1 = -3*-3 + b
-1 = 9 + b
b = -10
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Equation:
y = -3x - 10
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Cheers,
Stan H.
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