mấy bn ơi, giúp mk nhanh vs nha!!!!!!!!!!!
a/ A = 2x2 + y2 - 2xy - 2x + 3
= (x2 - 2xy + y2) + (x2 - 2x + 1) + 2
= (x - y)2 + (x - 1)2 + 2\(\ge2\)
b/ B = x2 - 2xy + 2y2 + 2x - 10y + 17
= (x2 - 2xy + y2) + 2(x - y) + 1 + (y2 - 8y + 16)
= (x - y + 1)2 + (y - 4)2 >= 0
\(a,A=2x^2+y^2-2xy-2x+3\)
\(=\left(x^2-2xy+y^2\right)+\left(x^2-2x+1\right)+2\)
\(=\left(x-y\right)^2+\left(x-1\right)^2+2\ge2\)\
Dấu = xảy ra khi:
\(x-y=0\Rightarrow x=y\)
\(x-1=0\Rightarrow x=1\)
Vậy Amin = 2 tại x = y = 1