Unformatted text preview: Q in R . (b) Use deﬁnitions and ideas from your lecture notes to prove that I is dense in R . (c) If D is a dense subset of R , prove that D must be inﬁnite. Proof by contradiction is useful here. 5. Pages 106111 # 1(iv), (vi) (Just do the calculations; no proofs); 3(i), (ii); 10(d); 13; 17(a); 18; 19. 6. Give a proof of Theorem 1 on pages 9899 that does not involve contradiction. 7. Let f ( x ) = x + 3 2 x . Prove that lim x → a f ( x ) = f ( a ) for all a 6 = 0. 8. Prove carefully that for all n ∈ N , lim x → n [ x ] does not exist. 9. Let D ⊂ R and let f : D → R be a function. Given a real number a , if lim x → a f ( x ) = l and l > 0, prove there exists a δ > 0 such that f ( x ) > 0 for all x ∈ D ∩ ( aδ,a + δ ) but x 6 = a . 10. Page 117 # 1(i); 3; 4....
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 Winter '08
 Vadim
 Calculus, mathematical sciences, Scarborough Department of Computer and Mathematical Sciences, Sciences MATA37 Calculus, Mathematical Sciences Summer

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