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Math Help - Equation of a line

  1. #1
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    Equation of a line

    Find the equation of the line through (2,-1) parallel to the line 3x + y = 7

    This section has got me all confused, What I got tried to do was:

    3x = 7 + y
    x = 7/3 + y/3

    y - 1 = 7/3 (x-2)
    3(y - 1) = 7 (x-2)
    3y - 3 = 7x - 14
    -7x + 3y = -14 + 3
    7x - 3y = 14 - 3
    7x - 3y = 11

    3x + y = 5 is the right answer I just don't what what the hell is going wrong, probably got it all messed up.
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  2. #2
    MHF Contributor red_dog's Avatar
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    y=-3x+7. The slope of this line is -3.

    Then the equation of the line parallel to it is

    y+1=-3(x-2)
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