5x²y-[2²y-(3xy-xy²)-3x²]-2xy²-y²化简求_数学解答

5x²y-[2²y-(3xy-xy²)-3x²]-2xy²-y²
化简
求值
x=-3,y=-7

人气：249 ℃　时间：2019-10-05 03:53:19

解答

少了个x5x²y-[2x²y-(3xy-xy²)-3x²]-2xy²-y²=5x²y-[2x²y-3xy+xy²-3x²]-2xy²-y²=5x²y-2x²y+3xy-xy²+3x²-2xy²-y²=3x²...