Recent content by alphonsas

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    Is the Set of All Algebraic Numbers Countable?

    Homework Statement A complex number z is said to be algebraic if there are integers a0; a1...; an not all zero such that z is a root of the polynomial, Prove that the set of all algebraic numbers is countable. Homework Equations The Attempt at a Solution For every natural...
  2. A

    Proving Sets and Functions Homework: f(f^-1(C)) = [C Intersection Im(f)]

    I am sorry, that C.. how can I prove that y belongs to c intersection im(f)?
  3. A

    Proving Sets and Functions Homework: f(f^-1(C)) = [C Intersection Im(f)]

    Homework Statement f: A -> B is a function with C a subset of B. Prove that f(f^-1(C)) = [C intersection Im(f)]. (f^-1(c) = f inverse of C) Homework Equations The Attempt at a Solution Please let me know how to approach to the solution (not using venn diagrams). Also if...