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Math Help - Urgent graph question help needed

  1. #1
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    Urgent graph question help needed

    Hello

    Im a bit stuck on this question:

    Find the equation of line CD where -

    C = (8,-3)
    D = (4,-4)

    Then show it meets the y axis at (0,-5)

    Thanks in advanced.
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  2. #2
    GAMMA Mathematics
    colby2152's Avatar
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    Quote Originally Posted by nugiboy View Post
    Hello

    Im a bit stuck on this question:

    Find the equation of line CD where -

    C = (8,-3)
    D = (4,-4)

    Then show it meets the y axis at (0,-5)

    Thanks in advanced.
    You have two points, so in essence you are just connecting the dots. Use the equation of the slope:

    slope = \frac{rise}{run} \Rightarrow m = \frac{y_1-y_2}{x_1-x_2}

    m = \frac{1}{4}

    Plug that in slope-intercept form.

    y=mx+b where b is the y-intercept, it should end up being -5 in this case

    Now, plug one of the coordinates in to find b

    -4=4\frac{1}{4}+b

    b = -5

    y = \frac{1}{4}x-5
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