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Treat fixed points as candidate limits before proving decrease

The sequence satisfies xn+1=12/(7−xn)x_{n+1}=12/(7-x_n) for positive integers nn.

(i) Find the exact value(s) of ss, the limit of xnx_n. marks

(ii) Show that if 3<xn<43<x_n<4, then xn+1<xnx_{n+1}<x_n. marks

[2008/TJC/JC1/MYE/6]

CJC · Review problems · Question 13

Subtract x_n and factor the resulting rational expression; keep the sign of its denominator.

Read the worked solution