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C4, however probably most will be able to help. watch

    • Thread Starter

    Hi so I am resitting C4 because I was one mark off an A overall and I haven't done maths since last June so it's all a bit foreign right now.

    I am doing adding and subtracting polynomials right now and I have come across a problem with showing a polynomial is bigger than a number.

    The question is-

    Given that x>0, show that (x/(x+2)) + ((x+1)(x+6)/(x^2+2x)) >2

    So I have got to the stage where I have (2x+3)/x (I've done all the actual subtracting polynomials work) but how do I show that it's bigger than 2?? I tried putting (2x+3)/x = 0 and = 2 but it's not helping my mind blockage.

    Can anyone put me out of my misery please? I am assuming it is such a dead easy thing to do, I just can't remember how to do it. Thanks guys

    If x>0 then (2x+3)/x = 2 + 3/x > 2 since 3/x > 0

    \dfrac{2x+3}{x} = 2 + \dfrac{3}{x}

    Now given that x > 0, what can you guarantee about the value of \dfrac{3}{x}?
    • Thread Starter

    Ahhh you split it up and then because 3/x is always bigger than 0, then that makes the answer always bigger than 2. I can't believe how obvious that is and I couldn't even see it lol. Thank you
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Updated: January 16, 2010
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