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International Mathematical Arhimede Contest (IMAC)
2013 IMAC Arhimede
6
6
Part of
2013 IMAC Arhimede
Problems
(1)
\sum_{i=1}^{n} \prod_{j\ne i} (x_i-x_j)^p\ge 0
Source: IMAC Arhimede 2013 p6
5/6/2019
Let
p
p
p
be an odd positive integer. Find all values of the natural numbers
n
≥
2
n\ge 2
n
≥
2
for which holds
∑
i
=
1
n
∏
j
≠
i
(
x
i
−
x
j
)
p
≥
0
\sum_{i=1}^{n} \prod_{j\ne i} (x_i-x_j)^p\ge 0
i
=
1
∑
n
j
=
i
∏
(
x
i
−
x
j
)
p
≥
0
where
x
1
,
x
2
,
.
.
,
x
n
x_1,x_2,..,x_n
x
1
,
x
2
,
..
,
x
n
are any real numbers.
inequalities
algebra
Sums and Products
Product
Sum