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2010 IMC
3
IMC 2010 - Problem 3
IMC 2010 - Problem 3
Source:
July 26, 2010
limit
function
real analysis
real analysis unsolved
Problem Statement
Define the sequence
x
1
,
x
2
,
.
.
.
x_1, x_2, ...
x
1
,
x
2
,
...
inductively by
x
1
=
5
x_1 = \sqrt{5}
x
1
=
5
and
x
n
+
1
=
x
n
2
−
2
x_{n+1} = x_n^2 - 2
x
n
+
1
=
x
n
2
−
2
for each
n
≥
1
n \geq 1
n
≥
1
. Compute
lim
n
→
∞
x
1
⋅
x
2
⋅
x
3
⋅
.
.
.
⋅
x
n
x
n
+
1
\lim_{n \to \infty} \frac{x_1 \cdot x_2 \cdot x_3 \cdot ... \cdot x_n}{x_{n+1}}
lim
n
→
∞
x
n
+
1
x
1
⋅
x
2
⋅
x
3
⋅
...
⋅
x
n
.
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