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  • 26-05-2009 3:08pm
    #1
    Elmo
    Registered Users Posts: 23,641 ✭✭✭✭


    Was just reading over some papers that I sat (not so long ago). I couldn't answer any of the questions now. I know in Honours maths I got the first 2 algerbra questions completely right (I saw the paper after the LC).

    but

    x + y = 1
    x^2 + y^2 = 25

    I am guessing that x and y both = 25. ????? That's totally wrong!!!

    Anyway good luck with the exams.


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    #2
    Nihilist21
    Registered Users Posts: 131 ✭✭Nihilist21


    I don't quite know if you were asking for the solution to that there, but I'll answer it anyway:

    x + y=1
    x^2 + y^2= 25

    x= 1-y

    sub this into the second:

    (1-y)^2 + y^2 = 25

    1-2y+2y^2=25
    2y^2 -2y -24=0

    solve that to get y= 4 / y= -3

    sub those values back into the first equation and you get x = -3 / x = 4.


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    #3
    Elmo
    Registered Users Posts: 23,641 ✭✭✭✭Elmo


    I remember doing it in the exam :D


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