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New Zealand Contests
New Zealand MO
2019 New Zealand MO
8
8
Part of
2019 New Zealand MO
Problems
(1)
\prod_{i=1}^{X_n} \frac{x_i}{s + 1 - x_i} + \prod_{i=1}^{Y_n} (1 - x_i) \le 1
Source: New Zealand MO 2019 Round 1 p8
9/20/2021
Suppose that
x
1
,
x
2
,
x
3
,
.
.
.
x
n
x_1, x_2, x_3, . . . x_n
x
1
,
x
2
,
x
3
,
...
x
n
are real numbers between
0
0
0
and
1
1
1
with sum
s
s
s
. Prove that
∏
i
=
1
n
x
i
s
+
1
−
x
i
+
∏
i
=
1
n
(
1
−
x
i
)
≤
1.
\prod_{i=1}^{n} \frac{x_i}{s + 1 - x_i} + \prod_{i=1}^{n} (1 - x_i) \le 1.
i
=
1
∏
n
s
+
1
−
x
i
x
i
+
i
=
1
∏
n
(
1
−
x
i
)
≤
1.
algebra
inequalities