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22 April, 09:27

8x-4y=-4

x=y-4

solve by substitution

+3
Answers (2)
  1. 22 April, 10:49
    0
    x = 3, y = 7

    Step-by-step explanation:

    Solve the following system:

    {8 x - 4 y = - 4

    x = y - 4

    Hint: | Perform a substitution.

    Substitute x = y - 4 into the first equation:

    {8 (y - 4) - 4 y = - 4

    x = y - 4

    Hint: | Expand the left hand side of the equation 8 (y - 4) - 4 y = - 4.

    8 (y - 4) - 4 y = (8 y - 32) - 4 y = 4 y - 32:

    {4 y - 32 = - 4

    x = y - 4

    Hint: | Choose an equation and a variable to solve for.

    In the first equation, look to solve for y:

    {4 y - 32 = - 4

    x = y - 4

    Hint: | Isolate terms with y to the left hand side.

    Add 32 to both sides:

    {4 y = 28

    x = y - 4

    Hint: | Solve for y.

    Divide both sides by 4:

    {y = 7

    x = y - 4

    Hint: | Perform a back substitution.

    Substitute y = 7 into the second equation:

    {y = 7

    x = 3

    Hint: | Sort results.

    Collect results in alphabetical order:

    Answer: {x = 3, y = 7
  2. 22 April, 11:06
    0
    8x-4y=-4

    8 (y-4) - 4y=-4

    8y-32-4y=-4

    8y-4y=-4+32

    4y=28

    y=28/4

    y=7
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