作业帮(5)先化简,再求值:3x2y-[2x2y-(2xy-3x2y)]+3xy2,其中x=3,y=-1/3(5)先化简,再求值：3x2y－[2x2y－(2xy－3x2y)]＋3xy2,其中x＝3,y＝1/3
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![(5)先化简,再求值:3x2y-[2x2y-(2xy-3x2y)]+3xy2,其中x=3,y=-1/3(5)先化简,再求值：3x2y－[2x2y－(2xy－3x2y)]＋3xy2,其中x＝3,y＝1/3](/uploads/image/z/6938981-53-1.jpg?t=%285%29%E5%85%88%E5%8C%96%E7%AE%80%2C%E5%86%8D%E6%B1%82%E5%80%BC%3A3x2y-%5B2x2y-%282xy-3x2y%29%5D%2B3xy2%2C%E5%85%B6%E4%B8%ADx%3D3%2Cy%3D-1%2F3%285%29%E5%85%88%E5%8C%96%E7%AE%80%2C%E5%86%8D%E6%B1%82%E5%80%BC%EF%BC%9A3x2y%EF%BC%8D%5B2x2y%EF%BC%8D%282xy%EF%BC%8D3x2y%29%5D%EF%BC%8B3xy2%2C%E5%85%B6%E4%B8%ADx%EF%BC%9D3%2Cy%EF%BC%9D1%2F3)
(5)先化简,再求值:3x2y-[2x2y-(2xy-3x2y)]+3xy2,其中x=3,y=-1/3(5)先化简,再求值：3x2y－[2x2y－(2xy－3x2y)]＋3xy2,其中x＝3,y＝1/3
(5)先化简,再求值:3x2y-[2x2y-(2xy-3x2y)]+3xy2,其中x=3,y=-1/3
(5)先化简,再求值：3x2y－[2x2y－(2xy－3x2y)]＋3xy2,其中x＝3,y＝1/3
(5)先化简,再求值:3x2y-[2x2y-(2xy-3x2y)]+3xy2,其中x=3,y=-1/3(5)先化简,再求值：3x2y－[2x2y－(2xy－3x2y)]＋3xy2,其中x＝3,y＝1/3
3x^2y－[2x^2y－(2xy－3x^2y)]＋3xy^2
=3x^2y－[2x^2y－2xy+3x^2y]＋3xy^2
=3x^2y－5x^2y+2xy＋3xy^2
=-2x^2y+2xy＋3xy^2
=-2*3^2*(-1/3)+2*3*(-1/3)+3*3*(-1/3)^2
=6-2+1
=5
3x2y－[2x2y－(2xy－3x2y)]＋3xy2
=3x²y-[2x²y-2xy+3x²y]+3xy²
=3x²y-5x²y+2xy+3xy²
=-2x²y+2xy+3xy²
x=3,y=-1/3时
原式=-2×2²×(-1/3)+2×3×(-1/3)+3×3×(-1/3)²
=5/3
3x2y－[2x2y－(2xy－3x2y)]＋3xy2
=3x²y-2x²y+2xy-3x²y+3xy²
=-2x²y+2xy+3xy²
=-6+2+1
=-3 y=1/3? 还是-1/3 我算的是1/3
数理答疑团为您解答，希望对你有所帮助。
3x2y－[2x2y－(2xy－3x2y)]＋3xy2
=3x²y-[2x²y-2xy+3x²y]+3xy²
=3x²y-5x²y+2xy+3xy²
=-2x²y+2xy+3xy²
=xy(-2x+2+3y)
当x=3,...
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数理答疑团为您解答，希望对你有所帮助。
3x2y－[2x2y－(2xy－3x2y)]＋3xy2
=3x²y-[2x²y-2xy+3x²y]+3xy²
=3x²y-5x²y+2xy+3xy²
=-2x²y+2xy+3xy²
=xy(-2x+2+3y)
当x=3,y=1/3时
原式= 1*(-6 + 2 +1）= -3
祝你学习进步，更上一层楼！ (*^__^*)
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