Algebra....HELP!!

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Solve the elimination method

7a + 6b = 3
-7a +b = 25

The solution of the system is?

  • Algebra....HELP!! -

    7a + 6b = 3
    -7a + b = 25

    b = 7a + 25

    Solve for a
    7a + 6(7a + 25) = 3
    7a + 42a + 150 = 3
    49a + 150 = 3
    49a = -147
    a = -3

    Solve for b
    -7(-3) + b = 25
    21 + b = 25
    b = 4

    Check answers
    7a + 6b = 3
    7(-3) + 6(4) = 3
    -21 + 24 = 3

    -7a + b = 25
    -7(-3) + 4 = 25
    -21 + 4 = 25

    Answers:
    a = -3
    b = 4

  • Algebra....HELP!! -

    7 a + 6 b = 3

    +

    -7 a + b = 25
    ________________

    7 a + ( - 7 a ) + 6 b + b = 3 + 25

    7 b = 28 Divide both sides by 7

    7 b / 7 = 28 / 7

    b = 4


    7 a + 6 b = 3

    7 a + 6 * 4 = 3

    7 a + 24 = 3 Subtract 24 to both sides

    7 a + 24 - 24 = 3 - 24

    7 a = - 21 Divide both sides by 7

    7 a / 7 = - 21 / 7

    a = - 3


    Proof :

    -7 a + b = 25

    - 7 * ( - 3 ) + 4 = 25

    21 + 4 = 25

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