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Math Help - Linear Equations: Point-slope Form

  1. #1
    4AM
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    Linear Equations: Point-slope Form

    Hi, I'm having trouble figuring out these equations. I can find the answer when the numbers are whole numbers, but when they're fractions and decimals, I always get them wrong.



    "Write an equation of the line that passes through the given points."

    a) (-1/2, -5); m = -1/2
    b) (-2, 1); m = 1.5
    c) (1.5, 2) and (-1.5, -7)

    I appreciate any help given!
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  2. #2
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    You are given the slope and a point, so you need to put this in point slope form and solve for y.

    y - y1 = m ( x - x1)

    y - ( -5) = -1/2 (x - (-1/2))

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

    y = -1/2x - 21/4
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  3. #3
    4AM
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    Quote Originally Posted by dashreeve View Post
    You are given the slope and a point, so you need to put this in point slope form and solve for y.

    y - y1 = m ( x - x1)

    y - ( -5) = -1/2 (x - (-1/2))

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

    y = -1/2x - 21/4
    How did you get from -1/4 to -21/4 though?
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  4. #4
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    Quote Originally Posted by 4AM View Post
    How did you get from -1/4 to -21/4 though?
    Typo.
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  5. #5
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    Quote Originally Posted by 4AM View Post
    How did you get from -1/4 to -21/4 though?
    subtracting 5 from each side, 21/4 or 5 and 1/4
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