There is a sequence
, , , ,
Find .
Solution: Assume that the sequence is a recursive sequence. The existence of the limit of such a sequence is often judged by the monotonic bounded criterion. For this question, obviously, there are
,
Therefore, the sequence increases monotonically.
The following uses mathematical induction to prove that the sequence is bounded:
Because , assuming , then we have
.
Therefore is bounded. According to criterion II, exists.
Suppose , we know from the sign preservation property of the limit of the sequence, , because
,
Right now
,
Therefore, taking the limits on both ends of the above equation , we get
,
Right now
,
Solving the above quadratic equation, we get
or ( reject ) .
so
.
For the graphics experiment of this example, see Experiment 1.9 of §1.3 .