若X加Y等于4,则多项式2分之1(X加Y)减3(X减Y)减2分之3(X加Y)减X加Y的直
问题描述:
若X加Y等于4,则多项式2分之1(X加Y)减3(X减Y)减2分之3(X加Y)减X加Y的直
答
1/2(x+y)+4(x-y)-3(x-y)-3/2(x+y)-x+y=1/2(x+y)+(x-y)-3/2(x+y)-(x-y)=-(x+y)=-4