| 3x2y-4xy2-3+5x2y+2xy2+5. |
答案:
| 3x2y-4xy2-3+5x2y+2xy2+5 =3x2y+5x2y-4xy2+2xy2-3+5 =(3x2y+5x2y)+(-4xy2+2xy2)+(-3+5) =(3+5)x2y+(-4+2)xy2+(-3+5) =8x2y-2xy2+2. |

| 3x2y-4xy2-3+5x2y+2xy2+5. |
答案:
| 3x2y-4xy2-3+5x2y+2xy2+5 =3x2y+5x2y-4xy2+2xy2-3+5 =(3x2y+5x2y)+(-4xy2+2xy2)+(-3+5) =(3+5)x2y+(-4+2)xy2+(-3+5) =8x2y-2xy2+2. |