分解因式:(1)x²+3xy+2y²+2x+4y (2)x²-2xy-10y²+x+9y-2

问题描述:

分解因式:(1)x²+3xy+2y²+2x+4y (2)x²-2xy-10y²+x+9y-2

(1)把3xy写成xy+2xy
就可以写成x(x+y+2)+2y(y+x+2)=(x+2y)(x+y+2)

x²+3xy+2y²+2x+4y
=(x+y)(x+2y)+2(x+2y)
=(x+y+2)(x+2y)
是-3xy吧
x²-3xy-10y²+x+9y-2
=(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)
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