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Pre-Calculus

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I have to use the substitution method to solve the system of equations.

4x-y=9 and 2x+3y=12

I worked this problem myself and could not find a possible solution. So I put that it is inconsistent. Is that correct? If not could you please help me?

  • Pre-Calculus - ,

    from the 1st ---> 4x-9 = y
    sub that into the 2nd

    2x + 3(4x-9) = 12
    2x + 12x - 27 = 12
    14x = 39
    x = 39/14
    y = 4(39/14) - 9 = 15/7

    check:
    1st:
    LS = 4(39/14) - 15/7
    = 156/14 - 30/14
    = 126/14 = 9 = RS
    2nd:
    LS = 2(39/14) + 3(15/7)
    = 39/7+ 45/7
    = 84/7 = 12 = RS

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