(½ x²y+1/5 xy²-¼xy)·(-½xy²),其中x=-2 y=-½ 就一道数学题而已
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![(½ x²y+1/5 xy²-¼xy)·(-½xy²),其中x=-2 y=-½ 就一道数学题而已](/uploads/image/z/1101680-8-0.jpg?t=%EF%BC%88%26%23189%3B+x%26%23178%3By%EF%BC%8B1%EF%BC%8F5+xy%26%23178%3B%EF%BC%8D%26%23188%3Bxy%29%C2%B7%28-%26%23189%3Bxy%26%23178%3B%29%2C%E5%85%B6%E4%B8%ADx%3D-2+y%3D-%26%23189%3B+%E5%B0%B1%E4%B8%80%E9%81%93%E6%95%B0%E5%AD%A6%E9%A2%98%E8%80%8C%E5%B7%B2)
(½ x²y+1/5 xy²-¼xy)·(-½xy²),其中x=-2 y=-½ 就一道数学题而已
(½ x²y+1/5 xy²-¼xy)·(-½xy²),其中x=-2 y=-½ 就一道数学题而已
(½ x²y+1/5 xy²-¼xy)·(-½xy²),其中x=-2 y=-½ 就一道数学题而已
=xy/20*(10x+4y-5)*(-xy²/2)
=-x²y³/40*(10x+4y-5)
当x=-2,y=-1/2时
原式=1/80*(-5-2-5)
=-3/20