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    The question is

    given y=\sqrt {x-1} show that x^2=y^4+2y^2+1

    I'm not entirely sure what I am meant to do here, have tried somethings but they were way off, so if anyone could help me I would be grateful.
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    cmon man this is easy. dont embarrass yourself. think about it first
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    haha i realise that and feel it's staring me in the face but no luck could you give me a hint to the first step at least might be able to get it from there
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    (Original post by semercer)
    haha i realise that and feel it's staring me in the face but no luck could you give me a hint to the first step at least might be able to get it from there
    try and get x^2 on its own. Do u know the first step?
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    if u really cant do it ill give u the solution. but the first step has got to be getting rid of the square root. u also see that u want y^4 and x^2, this should give u a clue what to do.
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    so I did this probably wrong but

    y=sqrtx-1
    y^2=x-1
    x^2=(x-1)^2+2(x-1)+1
    x^2=(x-1)(x-1)+2x-1
    x^2=x^2-2x+2x+1-1
    x^2=x^2
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    (Original post by semercer)
    so I did this probably wrong but

    y=sqrtx-1
    y^2=x-1
    x^2=(x-1)^2+2(x-1)+1
    x^2=(x-1)(x-1)+2x-1
    x^2=x^2-2x+2x+1-1
    x^2=x^2
    y=sqrtx-1y^2=x-1

    this is right up to here. just try and get x^2 from whats in bold and get it on its own.
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    k so i added 1 to both sides and squared again to get

    y^4+1=x^2

    this can't be right tho am missing the 2y^2 I tried this earlier
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    (Original post by semercer)
    k so i added 1 to both sides and squared again to get

    y^4+1=x^2

    this can't be right tho am missing the 2y^2 I tried this earlier
    maybe its just late. you added the 1 correctly, but u suddenly have y^4.
    it should be y^2+1=x
    then u square both sides, so (y^2+1)^2=x^2

    you then simply expand the bracket and get the answer
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    omg damn I'd like to agree with ya lol but maybe i'm just a little brain damaged haha
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    (Original post by semercer)
    omg damn I'd like to agree with ya lol but maybe i'm just a little brain damaged haha
    are you ****ing trolling?
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    (Original post by iamgreatness)
    are you ****ing trolling?
    I was kidding haha I hadn't slept for about a day when I came to do the question although it was still blindingly obvious, the work had to be in the next day ya see
 
 
 
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