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Unformatted text preview: n k 2 n = c n ( 2)-n . We know that c n 0 as n (see the previous exercise sheet). Therefore, by ratio test, the series n =1 c n ( 2)-n converges. Now the comparison theorem implies that the series n =1 (-1) n n k 1+2 n is also convergent. 5(iv). We have lim n-1 n +1 = 1. The ratio test implies that the series converges for all x such that | x + 1 | < 2. If | x + 1 | 2 then the sequence ( n-1) ( x +1) n ( n +1) 2 n does not converge to 0 and, consequently, the series diverges. 1...
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This document was uploaded on 01/31/2011.
- Spring '09