4x-3y-[-3+x+x-y]-5x =4x-3y+3-2x+y-5x=-3x-2y+3去括号先从里面去 后依次向外 一样的要合并4xy²-3x²y-{3x²+xy²-[2xy²-4x²y+(x²y-2xy²)]}=4xy²-3x²y-3x²-xy&...