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Math Help - Please help me

  1. #1
    Junior Member
    Joined
    Jun 2005
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    Unhappy Please help me

    Write an equation in slope-intercept from of a line with the following characteristics: perpendicular to the graph of 2x - 3y = 12 and passing through the point at (4,3).

    I'm lost here. Can someone help me with problem.
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  2. #2
    MHF Contributor
    Joined
    Apr 2005
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    Perpendicular lines have slopes that are negative reciprocals.
    Meaning, m1 = -1/m2
    or, m2 = -1/m1.

    So we find first the slope of the known line:
    2x -3y = 12
    Transform it to y = mx +b,
    -3y = -2x +12
    y = (-2 / -3)x +12/(-3)
    y = (2/3)x -4
    So, its slope is 2/3.

    Then, the slope of the unknown line is -3/2.
    The slope-intercept form (or y = mx +b) of its equation then is
    y = (-3/2)x +b

    Since this unknown line is passing through point (4,3), then,
    3 = -(3/2)*4 +b
    3 = -6 +b
    3+6 = b
    b = 9

    Therefore, the unknown line is
    y = -(3/2)x +9 ----answer.
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  3. #3
    Junior Member
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    Thank you.
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