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13 February, 08:31

Solve the system of equations by substitution 3x+y=9z

-5x+2y=4z what is the value for the y from the first equation, that could be substituted into the second equation?

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  1. 13 February, 08:34
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    x = 1.27

    y = 5.18

    Step-by-step explanation:

    to solve this system of equation by simultaneous equation we say that let

    3x+y=9 ... equation 1

    -5x+2y=4 ... equation 2

    from equation 1

    3x+y=9 ... equation 1

    y = 9 - 3x ... equation 3

    substitute the value of y = 9 - 3x into equation 2

    -5x+2y=4 ... equation 2

    -5x + 2 (9 - 3x) = 4

    -5x + 18 - 6x = 4

    collect the like terms

    18 - 4 = 6x + 5x

    14 = 11x

    divide both side by 11

    14/11 = 11x/11

    x = 14/11

    x = 1.27

    put the value of x = 1.27 into equation 3

    y = 9 - 3x ... equation 3

    y = 9 - 3 (1.27)

    y = 9 - 3.82

    y = 5.18

    to check if you are correct put the value of x and y into either equation 1 or equation 2.

    3x+y=9 ... equation 1

    3 (1.27) + 5.18 = 9

    3.81 + 5.18 = 9

    9 = 9
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