math

solve the following smultaneous equations
3x plus 2y =21 and x plus y = 8
3x -14y =0 and x - 4y plus 1 =0

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asked by lerato
  1. for the 1st pair, since you know what y is , just plug that value into the first equation and solve for x

    #2:

    3x - 14y = 0
    x - 4y + 1 = 0

    3x - 14y = 0
    multiply the 2nd by 3
    3x - 12y = -3
    subtract them
    -2y = 3
    y = -3/2
    sub into x - 4y = -1
    x - 4(-3/2) = -1
    x + 6 = -1
    x = -7

    x = -7, y = -3/2

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    posted by Reiny

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