5x^2+2y^2+2xy-14x-10y+17=(x^2+2xy+y^2)+(4x^2-14x-8)+ (y^2-10y+25)=(x+y)^2+(y-5)^2+2(2x+1)(x-4)约束条件只有(x+y)^2>=0,(y-5)^2>=0但最后一项系数为2,故可能的解为x+y,y-5相等或相反2x+1 与x-4相为相反数,并与...