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Math Help - Intersection of lines

  1. #1
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    Ville Platte Louisiana
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    Talking Intersection of lines

    At what point do the two lines whit the equations 7x-3y=13 and y=2x-3 intersect?

    This problem is for extra points, that I really need in my algebra II class.
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  2. #2
    Junior Member
    Joined
    Nov 2006
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    first off.. to find where two lines intersect.. we'll need to solve the system of equations..

    You have two equations

    7x - 3y = 13
    y = 2x - 3

    Since you already have the second equation solved for a variable (y in this case).. we can plug that expression into the first equation for y and solve.

    7x - 3(2x - 3) = 13
    7x - 6x + 9 = 13
    x + 9 = 13
    x = 4

    Now that we have the x-value where they intersect, we'll find the y-value by plugging the x-value into the second equation

    y = 2(4) - 3
    y = 8 - 3
    y = 5


    So, they intersect at the point (4, 5).
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  3. #3
    Senior Member
    Joined
    Apr 2006
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    Another way to find where they both intersect is to...graph them! Get each of the equations in y = form (standard form) and graph them. It's evident they intersect at (4, 5).
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