4x^2y^3(2x^2-3xy+5y^2)÷（-4x^2y^2)
=[(4x²y³)÷(-4x²y²)](2x²-3xy+5y²)
=-y(2x²-3xy+5y²)
=-2x²y+3xy²-5y³
不懂的欢迎追问.