~ Bạn tham khảo ~
`a, 5x^2(4x^3-7x+1/5)`
`= 20x^5-35x^3+x^2`
`b, (8x^3 - 6xy + 7)(-1/2xy)`
`= -4x^4y + 3x^2y^2 - 7/2xy`
`c, (4x^2 - 6x + 5)(2x-3)`
`= 8x^3 - 12x^2 + 10x - 12x^2 + 18x - 15`
`= 8x^3 -24x^2 + 28x - 15`
`d, (-2/3x^3-4xy^2+1/5)(2x-3y)`
`= -4/3x^4-8x^2y^2+2/5x+2x^3y+12xy^3-3/5y`