当x等于1,y等于2时,求代数式3xy2-【2xy2-2(xy-1.5x2y)】+xy-3x2y的值_数学解答

当x等于1,y等于2时,求代数式3xy2-【2xy2-2(xy-1.5x2y)】+xy-3x2y的值

人气：207 ℃　时间：2020-04-15 02:01:20

解答

解
3xy²-[2xy²-2(xy-1.5x²y)]+xy-3x²y
=3xy²-(2xy²-2xy+3x²y)+xy-3x²y
=3xy²-2xy²+2xy-3x²y+xy-3x²y
=xy²+3xy-6x²y
=1×4+3×1×2-6×1×2
=4+6-12
=-2