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Unformatted text preview: Modern Analysis, Homework 2 Due June 10, 2010 1. (2 pts) Suppose f : A B is a function. Prove that f is a bijection if and only if it is both injective (one-to-one) and surjective (onto). 2. (2 pts) Prove by induction that for all positive integers n , n X i =1 i = n ( n + 1) 2 . 3. (5 pts) Write down an explicit bijection N N N . Hint: count by diagonals and use problem 2. 4. (5 pts) Rudin, Ch 2, problem 2. If we havent talked about complex numbers in class, just read about them in Rudin. You may also assume the following result from algebra: let P ( x ) be a polynomial of degree d . Then P has at most d roots (this follows from the division algorithm). ( Just for fun: The set of algebraic integers is actually a field!!) 5. (1 pt) A complex number is called transcendental if it is not the root of any polynomial with integral coefficients. Show that the set of transcendentals is uncountable....
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This note was uploaded on 10/18/2011 for the course MATH S4061X taught by Professor Peters during the Spring '11 term at Columbia.
- Spring '11