4(3x²y-1/2xy²)-5(-xy²+3x²y),其中x=-1,y=2 先化简,再求值
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![4(3x²y-1/2xy²)-5(-xy²+3x²y),其中x=-1,y=2 先化简,再求值](/uploads/image/z/3809409-33-9.jpg?t=4%EF%BC%883x%26sup2%3By-1%2F2xy%26sup2%3B%EF%BC%89-5%EF%BC%88-xy%26sup2%3B%2B3x%26sup2%3By%EF%BC%89%2C%E5%85%B6%E4%B8%ADx%3D-1%2Cy%3D2+%E5%85%88%E5%8C%96%E7%AE%80%2C%E5%86%8D%E6%B1%82%E5%80%BC)
4(3x²y-1/2xy²)-5(-xy²+3x²y),其中x=-1,y=2 先化简,再求值
4(3x²y-1/2xy²)-5(-xy²+3x²y),其中x=-1,y=2 先化简,再求值
4(3x²y-1/2xy²)-5(-xy²+3x²y),其中x=-1,y=2 先化简,再求值
4(3x²y-1/2xy²)-5(-xy²+3x²y)
=12x²y-2xy²+5xy²-15x²y
=-3x²y+3xy²
=3xy(y-x)
=3*(-1)*2*(2-(-1))
=-6*3
=-18
12x²y-2xy²+5x²y-15x²y
=-3x²y+3x²y
=3xy(y-x)
=3*-1*2*3
=-18