(2)原式=1x1/4-12x1
= -11又3/4
18.原式=3x²y-(2x²y-6xy+3x²y)+xy
=3x²y-5x²y+6xy+xy
=-2x²y+7xy
=-xy(2x-7)
x=-1,y=-2带入得-xy(2x-7)=1x(-2)x(-1x2-7)=18
急来人啊十分钟限时答题,,要有序号啊,乱答差评
(2)原式=1x1/4-12x1
= -11又3/4
18.原式=3x²y-(2x²y-6xy+3x²y)+xy
=3x²y-5x²y+6xy+xy
=-2x²y+7xy
=-xy(2x-7)
x=-1,y=-2带入得-xy(2x-7)=1x(-2)x(-1x2-7)=18