1.x²-7x+122.x²+x-12 3.x²-4x-12 4.x²+10x-24 5.-x²-4x+216.(x-1)(x+4)-6用十字相乘法

1.x²-7x+12
2.x²+x-12 3.x²-4x-12 4.x²+10x-24 5.-x²-4x+21
6.(x-1)(x+4)-6
用十字相乘法

1（x-3)(x-4)
2(x+4)(x-3)
3(x-6）（x+2)
4(x+12)(x-2)
5-(x+7)(X-3)
6(x+5)(x-2)