Lời giải:
\((3x^{2m-1}-\frac{3}{7}y^{3n-5}+x^{2m}y^{3n}-3y^2).8x^{3-2m}y^{6-3n}\)
\(=3x^{2m-1}.8x^{3-2m}.y^{6-3n}-\frac{3}{7}y^{3n-5}.8x^{3-2m}y^{6-3n}+x^{2m}.y^{3n}.8x^{3-2m}y^{6-3n}-3y^2.8x^{3-2m}y^{6-3n}\)
\(=24x^{2m-1+3-2m}.y^{6-3n}-\frac{24}{7}y^{3n-5+6-3n}x^{3-2m}+8x^{2m+3-2m}y^{3n+6-3n}-24y^{2+6-3n}x^{3-2m}\)
\(=24x^2y^{6-3n}-\frac{24}{7}yx^{3-2m}+8x^3y^6-24y^{8-3n}x^{3-2m}\)