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2011 District Olympiad
4
Romania District Olympiad 2011 - Grade XI
Romania District Olympiad 2011 - Grade XI
Source:
March 12, 2011
function
analytic geometry
graphing lines
slope
inequalities
triangle inequality
real analysis
Problem Statement
Find all the functions
f
:
[
0
,
1
]
→
R
f:[0,1]\rightarrow \mathbb{R}
f
:
[
0
,
1
]
→
R
for which we have:
∣
x
−
y
∣
2
≤
∣
f
(
x
)
−
f
(
y
)
∣
≤
∣
x
−
y
∣
,
|x-y|^2\le |f(x)-f(y)|\le |x-y|,
∣
x
−
y
∣
2
≤
∣
f
(
x
)
−
f
(
y
)
∣
≤
∣
x
−
y
∣
,
for all
x
,
y
∈
[
0
,
1
]
x,y\in [0,1]
x
,
y
∈
[
0
,
1
]
.
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