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

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