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X

xuanquynh97

Đặt $P=x^2 +y^2-xy-x-y+2014$

$2P=2x^2+2y^2-2xy-2x-2y+4028$

$=(x^2-2xy+y^2)+x^2-2x+1+y^2-2y+1+4026$

$=(x-y)^2+(x-1)^2+(y-1)^2+4026$

\Rightarrow $MinP=4026:2=2013$ khi $x=y=1$
 
T

thaonhibmt2001@gmail.com

Trả lời

Đặt $A=x^2+y^2−xy−x−y+2014$

$2A=2x^2+2y^2−2xy−2x−2y+4028$

=$(x^2−2xy+y^2)+x^2−2x+1+y^2−2y+1+4026$

=$(x−y)^2+(x−1)^2+(y−1)^2+4026$
Khi x=y=1 thì

A=4026:2=2013 :khi:


Chú ý cách gõ talex
 
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