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Math Help - ´PArallel perpedicular or neither

  1. #1
    ChE
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    ´PArallel perpedicular or neither

    Y=-2+5
    Y=1/2x+4

    how do i know if the lines are parallel perpendicular or neither?
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  2. #2
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by ChE View Post
    Y=-2+5
    Y=1/2x+4

    how do i know if the lines are parallel perpendicular or neither?
    Two lines are parallel if they have the same slope.
    Two lines are perpendicular if the slopes obey: m_1 m_2 = -1.

    -Dan
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  3. #3
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    If the equations have the same gradient, then it is parallel.
    ex.
    y = 2x + 1
    y = 2x - 13
    the + or - just tells you how far up/down the y axis it is

    if, on the other hand, they are the same but the negative equivalent, then they are parallel
    ex.
    y = 2x + 1
    y = -2x - 13
    again, the + or - number doesnt matter; for example, +0.5x & -0.5x, +20,000x & -20,000, and +zx & -zx are all perpendicular to each other


    does this make sense?
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  4. #4
    Forum Admin topsquark's Avatar
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    Quote Originally Posted by kwah View Post
    if, on the other hand, they are the same but the negative equivalent, then they are parallel
    ex.
    y = 2x + 1
    y = -2x - 13
    again, the + or - number doesnt matter; for example, +0.5x & -0.5x, +20,000x & -20,000, and +zx & -zx are all perpendicular to each other
    This is not true. The lines
    y = mx + b_1
    y = -mx + b_2
    are not parallel (unless m happens to equal 0.) Nor are they perpendicular (unless m happens to equal 1.)

    -Dan
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  5. #5
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    Quote Originally Posted by topsquark View Post
    This is not true. The lines
    y = mx + b_1
    y = -mx + b_2
    are not parallel (unless m happens to equal 0.) Nor are they perpendicular (unless m happens to equal 1.)

    -Dan
    sorry i meant perpendicular with the value m=1 in mind .. my mistake ..

    you are right (as always) and i am wrong (as always) in that, when the values of m are multiplied, they result in a product of -1
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