解:3y(y-4)(2y+1)-(2y-3)(4y²+6y-9)=3y(2y²-7y-4)-(8y³+12y²-18y-12y²-18y+27)=6y³-21y²-12y-8y³+36y-27=-2y³-21y²+24y-27希望对你有帮助,望采纳,谢谢~
=(3y^2-12y)(2y+1)-(8y^3+12y^2-18y-12y^2-18y+27)=6y^3+3y^2-24y^2-12y-8y^3+36y-27=-2y^3-21y^2+24y-27