5x²+6xy-8y²-3x+8y-2
=(x+2y)(5x-4y)+2(x+2y)-(5x-4y)-2
=(x+2y)(5x-4y+2)-(5x-4y+2)
=(x+2y-1)(5x-4y+2)
怎样因式分解5x²+6xy-8y²-3x+8y-2
5x²+6xy-8y²-3x+8y-2
=(x+2y)(5x-4y)+2(x+2y)-(5x-4y)-2
=(x+2y)(5x-4y+2)-(5x-4y+2)
=(x+2y-1)(5x-4y+2)