令x+y=a,xy=b原式化为：（b-1）^2+(a+2)(a+2b)=b^2-2b+1+a^2+2a+2ab+4b=b^2+2b+1+a^2+2a+2ab=a^2+2ab+b^2+2a+2b+1=(a^2+2ab+b^2)+2(a+b)+1=(a+b)^2+2(a+b)+1=(a+b+1)^2=(xy+x+y+1)^2=[(x+1)(y+1)]^2=(x+1)^2*(y+1)^2...