已知想x(x-1)-(x二次-y)=2求2分之3(x2次)+3(y2次)-3xy的值
问题描述:
已知想x(x-1)-(x二次-y)=2求2分之3(x2次)+3(y2次)-3xy的值
答
把x(x-1)-(x二次-y)=2去括号,合并同类项整理得y-x=2
2分之3(x2次)+3(y2次)-3xy=3/2(x²+y²-2xy)=3/2(y-x)²=3/2×4=6