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Putnam
1978 Putnam
A5
Putnam 1978 A5
Putnam 1978 A5
Source: Putnam 1978
May 3, 2022
Putnam
trigonometry
inequalities
Jensen s Inequality
Problem Statement
Let
0
<
x
i
<
π
0 < x_i < \pi
0
<
x
i
<
π
for
i
=
1
,
2
,
…
,
n
i=1,2,\ldots, n
i
=
1
,
2
,
…
,
n
and set
x
=
x
1
+
x
2
+
…
+
x
n
n
.
x= \frac{ x_1 +x_2 + \ldots+ x_n }{n}.
x
=
n
x
1
+
x
2
+
…
+
x
n
.
Prove that
∏
i
=
1
n
sin
x
i
x
i
≤
(
sin
x
x
)
n
.
\prod_{i=1}^{n} \frac{ \sin x_i }{x_i } \leq \left( \frac{ \sin x}{x}\right)^{n}.
i
=
1
∏
n
x
i
sin
x
i
≤
(
x
sin
x
)
n
.
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