this is on AoPS ?
yup =))
LetterCorn Chưa có ai trong danh sách bạn bè.
31-10-2016 - 21:03
this is on AoPS ?
yup =))
29-10-2016 - 18:21
GT $\Leftrightarrow P=3(\sqrt{x+1}+\sqrt{y+2})(\Rightarrow P\geq 0)$
$\leq 3\sqrt{2(x+y+3)}=3\sqrt{2P+6}$
$\Leftrightarrow P^{2}\leq 18P+54\Leftrightarrow 9-\sqrt{35}\leq P\leq 9+\sqrt{35}$
Do đó
- $MIN(P)=9-\sqrt{35}\Leftrightarrow \left\{\begin{matrix} x=\frac{10-\sqrt{35}}{2} & & \\ y=\frac{8-\sqrt{35}}{2} & & \end{matrix}\right.$
- $MAX(P)=9+\sqrt{35}\Leftrightarrow \left\{\begin{matrix} x=\frac{10+\sqrt{35}}{2} & & \\ y=\frac{8+\sqrt{35}}{2} & & \end{matrix}\right.$
cách đúng r đó bạn , mỗi tội ấn máy sai ⇔
P2≤18P+54⇔9−√35≤P≤9+√35⇔P2≤18P+54⇔9−35≤P≤9+35
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