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Balkan MO Shortlist
2007 Balkan MO Shortlist
A1
A1
Part of
2007 Balkan MO Shortlist
Problems
(1)
Fin the minimum and maximum of the given function
Source: Balkan MO ShortList 2007 A1
4/6/2020
Find the minimum and maximum value of the function \begin{align*} f(x,y)=ax^2+cy^2 \end{align*} Under the condition
a
x
2
−
b
x
y
+
c
y
2
=
d
ax^2-bxy+cy^2=d
a
x
2
−
b
x
y
+
c
y
2
=
d
, where
a
,
b
,
c
,
d
a,b,c,d
a
,
b
,
c
,
d
are positive real numbers such that
b
2
−
4
a
c
<
0
b^2 -4ac <0
b
2
−
4
a
c
<
0
Tuzo nonsense