PLEASE HELP! SOLVE { X+Y=4 {7X+9Y=42

Question

PLEASE HELP!
SOLVE { X+Y=4
{7X+9Y=42

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Skylar 2 weeks 2021-10-07T17:54:48+00:00 2 Answers 0

Answers ( )

    0
    2021-10-07T17:56:12+00:00

    Answer:

    Step-by-step explanation:

    x + y = 4  —————(i)

    x = 4-y

    7x + 9y = 42 ———–(ii)

    Plug in x = 4-y in equ (ii)

               7*(4 – y) + 9y = 42

                 28 – 7y +9y = 42

                       28 + 2y = 42

                               2y = 42 – 28

                               2y = 14

                                y = 14/2

    y = 7

    x = 4 – y

    x = 4 – 7

    x = -3

    0
    2021-10-07T17:56:32+00:00

    Answer:

    use system of equations

    x+y=4

    7x+9y=42

    if we want to solve for y first

    then multiply the first equation by 7 to cancel out x

     7x+7y=28

    – 7x+9y=42

    -2y=-14

    y=7

    to solve for x just input y into the equation

    choose any equation u like from one of the two

    x+7=4

    x=4-7

    x=-3

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