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Math Help - proving

  1. #1
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    proving

    how do you prove that there is a rational number whose square is 9?

    sorry, i just started learning on proofs and have not much idea on how to think in order to solve this question..is there a certain method that i can use whenever i see proving questions?

    thanks!
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  2. #2
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    Quote Originally Posted by alexandrabel90 View Post
    how do you prove that there is a rational number whose square is 9?
    \left(\frac{3}{1}\right)^2=9
    Is that what you mean?
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  3. #3
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    You need to find m,n \in Z such that

    Here's a start.

    \left(\frac{m}{n}\right)^2 = 9

    \left(\frac{m}{n}\right)^2 = 3^2
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