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Math Help - Substitution Inequality

  1. #1
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    Substitution Inequality

    2x +3y = 5
    x
    +3xy = 4

    Okay, so I substitute y = -2/3x +5/3

    x
    +3x(-2/3x +5/3) -4

    I get '3x +5x -4'

    It doesn't factorise, so I use the formula and answers are decimals, but the answers in textbook are 1,1 and 4,-1

    ​So, what did I do wrong?
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  2. #2
    Forum Admin topsquark's Avatar
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    Re: Substitution Inequality

    Quote Originally Posted by quadling View Post
    2x +3y = 5
    x
    +3xy = 4

    Okay, so I substitute y = -2/3x +5/3

    x
    +3x(-2/3x +5/3) -4

    I get '3x +5x -4'

    It doesn't factorise, so I use the formula and answers are decimals, but the answers in textbook are 1,1 and 4,-1

    ​So, what did I do wrong?
    Check the coefficient of the x^2 again. x^2 - 2x^2 is....

    -Dan
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  3. #3
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    Re: Substitution Inequality

    ffs. sorry. thanks.
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