答：x²+xy-2y²-3x-12y-10=(x+2y)(x-y)-(3x+12y)-2×5利用十字相乘法有：x+2y 2xx-y -5有：-5(x+2y)+2(x-y)=-3x-12y所以：原式分解为：x²+xy-2y²-3x-12y-10=(x+2y)(x-y)-(3x+12y)-2×5=(x+2y+2)(...