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National and Regional Contests
Russia Contests
Saint Petersburg Mathematical Olympiad
2001 Saint Petersburg Mathematical Olympiad
10.1
10.1
Part of
2001 Saint Petersburg Mathematical Olympiad
Problems
(1)
Inequality on quadratic trinomials
Source: St. Petersburg MO 2001, 10th grade, P1
4/24/2023
Quadratic trinomials
f
f
f
and
g
g
g
with integer coefficients obtain only positive values and the inequality
f
(
x
)
g
(
x
)
≥
2
\dfrac{f(x)}{g(x)}\geq \sqrt{2}
g
(
x
)
f
(
x
)
≥
2
is true
∀
x
∈
R
\forall x\in\mathbb{R}
∀
x
∈
R
. Prove that
f
(
x
)
g
(
x
)
>
2
\dfrac{f(x)}{g(x)}>\sqrt{2}
g
(
x
)
f
(
x
)
>
2
is true
∀
x
∈
R
\forall x\in\mathbb{R}
∀
x
∈
R
[I]Proposed by A. Khrabrov
inequalities
quadratics
quadratic trinomial
algebra