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4
Functional inequality
Functional inequality
Source: Greek BMO TST 2015 Problem 4
April 5, 2015
function
inequalities
algebra
Problem Statement
Find all functions
f
:
R
→
R
f:\mathbb{R} \rightarrow \mathbb{R}
f
:
R
→
R
which satisfy
y
f
(
x
)
+
f
(
y
)
≥
f
(
x
y
)
yf(x)+f(y) \geq f(xy)
y
f
(
x
)
+
f
(
y
)
≥
f
(
x
y
)
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