4x^2 +9y^2-4x-6y+2=04x^2-4x+1+9y^2-6y+1=0(2x-1)^2+(3y-1)^2=0 ∴2x-1=0 3y-1=0 x=1/2 y=1/31/根号xy =根号6
(2x-1)^2+(3y-1)^2=0,x=1/2,y=1/3,所以=根号6