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Math Help - No rational number

  1. #1
    Super Member dhiab's Avatar
    May 2009

    No rational number

    Show that equation
    accepts a positive single resolution no rational.
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  2. #2
    Senior Member TheAbstractionist's Avatar
    Apr 2009
    As this is a polynomial of odd degree, it has at least one real solution. Using calculus (we are in the right section for using calculus here ) shows that the function f(x)=x^5+x-10 is strictly increasing for all x and so the equation has at most one real solution.

    So there is exactly one real solution. It remains to show that this solutiosn is positive and not rational. The former is easy: f(1)=-8<0 and f(2)=24>0 so the solution lies between x=1 and x=2. I leave the rest to you.
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