$D=(x^2-2xy+y^2)+(6x-6y)+9+(4y^2-12y+9)+32=(x-y)^2+6(x-y)+9+(2y-3)^2+32=(x-y+3)^2+(2y-3)^2+32\geq 32$Dấu = xảy ra khi $:x=\frac{-3}{2} , y=\frac{3}{2}$
$
E=(x^2-2xy+y^2)+(6x-6y)+9+(4y^2-12y+9)+32=(x-y)^2+6(x-y)+9+(2y-3)^2+32=(x-y+3)^2+(2y-3)^2+32\geq 32$Dấu = xảy ra khi $:x=\frac{-3}{2} , y=\frac{3}{2}$