已知x+y=4,xy=-12,则(x加1分之y加1)加(y加1分之x加1) 网上答案有错误,

(y+1)/(x+1)+(x+1)/(y+1)=(y+1)^2/[(x+1)(y+1)]+(x+1)^2/[(x+1)(y+1)]=[(y+1)^2+(x+1)^2]/[(x+1)(y+1)]=[y^2+2y+1+x^2+2x+1]/[x(y+1)+(y+1)]=[y^2+x^2+2x+2y+2]/[xy+x+y+1]=[y^2+x^2+2(x+y)+2]/[-12+4+1]=[y^2+x^2+2...