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13 December, 14:49

Solve the system of equations using multiplication.

3x + 8y = - 20

5x - y = - 19

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Answers (1)
  1. 13 December, 15:16
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    [tex]3x + 8y = - 20[tex]

    [tex]5x - y = - 19[tex]

    [tex]3x + 8y = - 20[tex]

    [tex]40x - 8y = - 152[tex] (multiply both sides by 8)

    Add the two equations together.

    [tex] (3x + 8y) + (40x - 8y) = - 20 + (-152) [tex]

    Which makes it

    [tex]43x = - 172[tex]

    Then divide 43 by both sides.

    [tex]x = - 4[tex]

    Then get [tex]y[tex] by substituting [tex]x[tex]

    [tex]5 * (-4) - y = - 19[tex]

    And solve the equation.

    [tex]5 * (-4) - y = - 19[tex]

    [tex]5 * (-4) - (-19) = y[tex]

    [tex]-20 + 19 = y[tex]

    [tex]y = - 1[tex]

    So the answer is:

    [tex]x = - 4, y = - 1[tex]
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