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Math Help - can anyone qive me the answer and explain how to work this question for future ref.

  1. #1
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    can anyone qive me the answer and explain how to work this question for future ref.

    using the point-slope form of the line: y - y_1 = m(x - x_1) to find the equation of the line passing through the points (5, -3) and (-1, 5)
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  2. #2
    Rhymes with Orange Chris L T521's Avatar
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    Quote Originally Posted by tyonna View Post
    using the point-slope form of the line: y - y_1 = m(x - x_1) to find the equation of the line passing through the points (5, -3) and (-1, 5)
    First find the slope:

    m=\frac{y_2-y_1}{x_2-x_1}=\frac{5-(-3)}{-1-5}=\frac{8}{-6}=-\frac{4}{3}.

    Now plug m and either point into y-y_0=m\left(x-x_0\right) and that will give you the line you're looking for.

    Can you try to finish this?
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    Quote Originally Posted by Chris L T521 View Post
    First find the slope:

    m=\frac{y_2-y_1}{x_2-x_1}=\frac{5-(-3)}{-1-5}=\frac{8}{-6}=-\frac{4}{3}.

    Now plug m and either point into y-y_0=m\left(x-x_0\right) and that will give you the line you're looking for.

    Can you try to finish this?
    Not really, as what you just said was kind of a foreign language to me. Sorry
    math is my worst subject!
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  4. #4
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    Quote Originally Posted by tyonna View Post
    Not really, as what you just said was kind of a foreign language to me. Sorry
    math is my worst subject!
    If that is the case then you need to go back and thoroughly review the pre-requisite material that this topic assumes you know how to do.
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  5. #5
    Grand Panjandrum
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    Quote Originally Posted by tyonna View Post
    using the point-slope form of the line: y - y_1 = m(x - x_1) to find the equation of the line passing through the points (5, -3) and (-1, 5)
    See the PurpleMath article, you need the second worked example.

    CB
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  6. #6
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    Oooh, I'd like to answer this as we just learned it yesterday .

    To get the equation of a line passing through two points, you need to know how to work out the gradient:

    m = \frac {y_2 - y_1}{x_2 - x_1}
    or:
    m = \frac {y_1 - y_2}{x_1 - x_2}

    So to work that out with your question:

    m = \frac {y_1 - y_2}{x_2 - x_1} = \frac{-3 - 5}{5 - (-1)} = \frac{-8}{6} = -\frac{4}{3}

    So you now have the gradient, -\frac{4}{3}. Now choose one of the coordinates, I'll use (5, -3).

    \begin{array}{rcrcrc}<br />
y - y_1 = m(x - x_1)\\<br />
y - (-3) = -\frac{4}{3}(x - 5)\\<br />
3(y + 3) = -4(x - 5)\\<br />
3y + 9 = -4x + 20\\<br />
3y = -4x + 11\\<br />
y = \frac{-4x + 11}{3}<br />
\end{array}

    I've checked that against both of your coordinates and it works, so look over those notes and you should be able to understand it .
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