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Thread: who can>hahahahaha

  1. #1

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    who can>hahahahaha

    solve this:
    2x^2=y +1/y
    and
    2y^2=x+1/x

  2. #2
    Junior Member phrodu's Avatar
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    x = 1
    y = 1

  3. #3
    Fanatic Member bugzpodder's Avatar
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    i solved your problem (see the post i made below)
    Last edited by bugzpodder; Jan 14th, 2003 at 09:44 PM.
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  4. #4
    So Unbanned DiGiTaIErRoR's Avatar
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    There are lots of imaginary solutions.


  5. #5
    pathfinder NotLKH's Avatar
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    Originally posted by bugzpodder
    2x^2=y +1/y
    and
    2y^2=x+1/x

    we establish and x>0 and y>0

    2x^2=(y^2+1)/y^2
    ....
    Are you sure?
    I think you meant:

    2x2 = (y2 + y)/(y2)

    ???
    -Lou

  6. #6
    Fanatic Member bugzpodder's Avatar
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    2x^2=y+1/y
    2y^2=x+1/x

    we establish that x>0,y>0

    fine i'll subtract them:

    2(x+y)(x-y)=y-x+1/y-1/x

    2(x+y)(x-y)=-(x-y)+(x-y)/xy

    (2x+2y+1-1/xy)(x-y)=0

    so x=y or

    2x+2y-1/xy+1=0

    2xy+2y^2-1/x+y=0 (multiply by y)

    replace 2y^2 with x+1/x

    2xy+x+y=0

    since x>0,y>0 therefore no solutions for this case.

    we establish x=y

    2x^2=x+1/x
    2x^3=x^2+1

    2x^3-x^2-1=0
    since x=1 is a solution, then:

    (x-1)(2x^2+x+1)=0

    since no solutions for 2x^2+x+1,

    so (x,y)=(1,1) is the only solution
    Last edited by bugzpodder; Dec 28th, 2002 at 09:53 AM.
    Massey RuleZ! ^-^__Cheers!__^-^ Massey RuleZ!


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    The probability that a random rational number has an even denominator is 1/3 (Salamin and Gosper 1972)? This result is independently verified by me (2002)!

  7. #7

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    Originally posted by bugzpodder
    i solved your problem (see the post i made below) but i bet you can't do this question, phan, hahahaha

    given a function f(x) of degree n and some prime p.
    f(0)=0
    f(1)=1
    f(x)=0 or 1 (mod p) for all integers x

    prove that n >= p-1

    note if a = b (mod c), then (a-b) is divisible by c
    u want me to solve this ?
    hehehe,if u bet i cant solve,why do u want to show me??KEEP WAITING!!!!!

  8. #8

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    Originally posted by bugzpodder
    2x^2=y+1/y
    2y^2=x+1/x

    we establish that x>0,y>0

    fine i'll subtract them:

    2(x+y)(x-y)=y-x+1/y-1/x

    2(x+y)(x-y)=-(x-y)+(x-y)/xy

    (2x+2y+1-1/xy)(x-y)=0

    so x=y or

    2x+2y-1/xy+1=0

    2xy+2y^2-1/x+y=0 (multiply by y)

    replace 2y^2 with x+1/x

    2xy+x+y=0

    since x>0,y>0 therefore no solutions for this case.

    we establish x=y

    2x^2=x+1/x
    2x^3=x^2+1

    2x^3-x^2-1=0
    since x=1 is a solution, then:

    (x-1)(2x^2+x+1)=0

    since no solutions for 2x^2+x+1,

    so (x,y)=(1,1) is the only solution

    did u solve that by urself?

  9. #9
    Fanatic Member bugzpodder's Avatar
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    yes of course i solved that by myself.
    Last edited by bugzpodder; Jan 14th, 2003 at 09:44 PM.
    Massey RuleZ! ^-^__Cheers!__^-^ Massey RuleZ!


    Did you know that...
    The probability that a random rational number has an even denominator is 1/3 (Salamin and Gosper 1972)? This result is independently verified by me (2002)!

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