因式分解:(1)x2-3xy-10y2+x+9y-2;(2)x3-11x2+31x-21.
1个回答

解题思路:(1)、(2)先添项、拆项、再提取公因式即可.

(1)原式=(x+2y)(x-5y)+2x+4y-x+5y-2

=(x+2y)(x-5y)+2(x+2y)-(x-5y+2)

=(x+2y)(x-5y+2)-(x-5y+2)

=(x+2y-1)(x-5y+2);

(2)原式=(x3-1)-(11x3-31x+20)

=(x-1)(x2+x+1)-(11x-20)(x-1)

=(x-1)(x2+x+1-11x+20)

=(x-1)(x2-10x+21)

=(x-1)(x-3)(x-7).

点评:

本题考点: 因式分解.

考点点评: 本题考查的是因式分解,在解答此类题目时要注意使用分组分解法.