MathDB
Problems
Contests
National and Regional Contests
USA Contests
USA - College-Hosted Events
BMT Problems
2015 BMT Spring
P1
2015 BMT Spring Analysis P1
2015 BMT Spring Analysis P1
Source:
January 20, 2022
complex numbers
inequalities
algebra
Problem Statement
Suppose
z
0
,
z
1
,
…
,
z
n
−
1
z_0,z_1,\ldots,z_{n-1}
z
0
,
z
1
,
…
,
z
n
−
1
are complex numbers such that
z
k
=
e
2
k
π
i
/
n
z_k=e^{2k\pi i/n}
z
k
=
e
2
kπi
/
n
for
k
=
0
,
1
,
2
,
…
,
n
−
1
k=0,1,2,\ldots,n-1
k
=
0
,
1
,
2
,
…
,
n
−
1
. Prove that for any complex number
z
z
z
,
∑
k
=
0
n
−
1
∣
z
−
z
k
∣
≥
n
\sum_{k=0}^{n-1}|z-z_k|\ge n
∑
k
=
0
n
−
1
∣
z
−
z
k
∣
≥
n
.
Back to Problems
View on AoPS