因式分解x^3+5xy-2y^2+x+9y-4
问题描述：
因式分解x^3+5xy-2y^2+x+9y-4
答
3X^2+5XY-2Y^2+X+9Y-4
=(x+2y)(3x-y)+x+9y-4
=(x+2y)(3x-y)+(4x+8y-3x+y)-4
=(x+2y)(3x-y)+4(x+2y)-(3x-y)-4
=(x+2y)(3x-y) -(3x-y)+4(x+2y) -4
=(x+2y-1)(3x-y)+4(x+2y-1)
=(x+2y-1)(3x-y+4)