已知x+y=[负4],xy=[负12],求分式[y+1/x+1]+[x+1/y+1]的值
人气：186 ℃ 时间：2019-10-19 15:42:00
解答
[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]/[xy+x+y+i]=[(y+x)^2-2xy+2x+2y+2]/[-12-4+1]=[(-4)^2-2(-12)+2(-4)+2]/(-15)=-510
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