作业帮先化简再求值3x²y-[2xy²-2（xy-3/2 x²y）]+3xy²,其中x=3 y= -1/3
来源：学生作业帮助网 编辑：作业帮 时间：2024/05/05 06:54:59
![先化简再求值3x²y-[2xy²-2（xy-3/2 x²y）]+3xy²,其中x=3 y= -1/3](/uploads/image/z/695964-12-4.jpg?t=%E5%85%88%E5%8C%96%E7%AE%80%E5%86%8D%E6%B1%82%E5%80%BC3x%26%23178%3By-%5B2xy%26%23178%3B-2%EF%BC%88xy-3%2F2+x%26%23178%3By%EF%BC%89%5D%2B3xy%26%23178%3B%2C%E5%85%B6%E4%B8%ADx%3D3+y%3D+-1%2F3)
先化简再求值3x²y-[2xy²-2（xy-3/2 x²y）]+3xy²,其中x=3 y= -1/3
先化简再求值3x²y-[2xy²-2（xy-3/2 x²y）]+3xy²,其中x=3 y= -1/3
先化简再求值3x²y-[2xy²-2（xy-3/2 x²y）]+3xy²,其中x=3 y= -1/3
3x²y-[2xy²-2（xy-3/2 x²y）]+3xy²
=3x²y-（2xy²-2xy+3x²y）+3xy²
=3x²y-2xy²+2xy-3x²y+3xy²
=-2xy²+2xy+3xy²
=xy²+2xy
=xy(y+2) x=3,y=-1/3
=-1(-1/3+2)
=-5/3
3x²y-[2xy²-2（xy-3/2 x²y）]+3xy²
=3x²y-（2xy²-2xy+3 x²y）+3xy²
=3x²y-2xy²+2xy-3 x²y+3xy²
=xy²+2xy
=xy（y+2）
x=3 y= -1/3 y=-1/9
x、y代进去得17/243