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1988 Irish Math Olympiad
10
Interesting Inequality
Interesting Inequality
Source: 1988 IrMO Paper 1 Problem 10
September 28, 2017
inequalities
Problem Statement
Let
0
≤
x
≤
1
0\le x\le 1
0
≤
x
≤
1
. Show that if
n
n
n
is any positive integer, then
(
1
+
x
)
n
≥
(
1
−
x
)
n
+
2
n
x
(
1
−
x
2
)
n
−
1
2
(1+x)^n\ge (1-x)^n+2nx(1-x^2)^{\frac{n-1}{2}}
(
1
+
x
)
n
≥
(
1
−
x
)
n
+
2
n
x
(
1
−
x
2
)
2
n
−
1
.
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