~ Bạn tham khảo ~
`a, (-2x^2y+1/2xy^2-3)(-2x^2y)`
`= 4x^4y^2-x^3y^3+6x^2y`
`b, 2x^2(5x^3-4x^2y-7xy+1/2)`
`= 10x^5-8x^4y-14x^3y+x^2`
`c, (x^2y-xy+xy^2+y^3)3xy^2`
`= 3x^3y^3-3x^2y^3+3x^2y^4+3xy^5`
`d, -3/7x^4(2,1y^2-0,7x+35)`
`= -3/7x^4(21/10y^2-7/10x+35)`
`= -9/10x^4y^2+3/10x^5-15x^4`