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Math Help - System of Equations

  1. #1
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    System of Equations

    Solve the following system of equations (please check if I did them correctly as it's been a while since I've taken math...):

    y = 2 + 6x

    y = 20 - 3x
    My answers: x = 2 and y = 14


    12x + 4y = 80

    2x + 4y = 20
    My answers: x = 6 and y = 2

    ---------------------

    The values of x and y that solve these two equations simultaneously can be seen on the graph as:
    a) the values of the intercepts of the two lines
    b) the slopes of the two lines
    c) the coordinates at which the two lines intersect
    d) the inverse of the slopes of the two lines

    y = 7 - \frac{1}{2}x (blue lines)

    y = 1 + x (orange line)
    My answer is a because the graph represents the values both equations demonstrate???
    Attached Thumbnails Attached Thumbnails System of Equations-graph132.png  
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  2. #2
    MHF Contributor
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    It is OK but for the last exercise the answer is c
    When you solve the system you can find x and y which are the coordinates of the intersection point of the 2 lines
    Btw the blue line does not correspond to y=7-x/2 since for x=0 you should get y=7
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  3. #3
    MHF Contributor

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    Note that "the values of the intercepts of both lines" does NOT mean the point where the two lines intersect: it means the values where the lines intersect the x or y axes. (The fact that "intercepts" is plural should be a warning!)
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