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Math Help - Show a set is countable

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    Show a set is countable

    Let E be the set of real numbers, x, satisfying

    ax^2+bx+c=0 for some a,b,c in Z

    Show that E is countable.
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    Quote Originally Posted by ashamrock415 View Post
    Let E be the set of real numbers, x, satisfying

    ax^2+bx+c=0 for some a,b,c in Z

    Show that E is countable.
    The cross product of two countable sets is countable. There can be at most two distinct real solutions per (a,b,c). The cardinality of E is at most the cardinality of Z x Z x Z x {0,1}.
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