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Greece Contests
Greece JBMO TST
2004 Greece JBMO TST
4
if b^3+b <= a-a^3 for a,b>0 then b<a<1 and a^2+b^2<1
if b^3+b <= a-a^3 for a,b>0 then b<a<1 and a^2+b^2<1
Source: Greece JBMO TST 2004 p4
June 18, 2019
algebra
inequalities
Problem Statement
Let
a
,
b
a,b
a
,
b
be positive real numbers such that
b
3
+
b
≤
a
−
a
3
b^3+b\le a-a^3
b
3
+
b
≤
a
−
a
3
. Prove that: i)
b
<
a
<
1
b<a<1
b
<
a
<
1
ii)
a
2
+
b
2
<
1
a^2+b^2<1
a
2
+
b
2
<
1
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