Question

初一的奥数题

分解因式：
3x^2+5xy-2y^2+x+9y-4

Answer 1

3x -y 4

x 2y -1

双十字因式分解~~~
得：
3x^2+5xy-2y^2+x+9y-4
=(3x-y+4)(x+2y-1)

或者：
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)

Answer 2

3x^2+5xy-2y^2+x+9y-4
=(3x-y)(x+2y)+x+9y-4
=(3x-y)(x+2y)+4(x+2y)-(3x-y)-4
=(3x-y+4)(x+2y-1)