3a²-7a-6 6x²-11xy+3y² 4m²+8mn+3n² 10x²-21xy+2y²
问题描述：
3a²-7a-6 6x²-11xy+3y² 4m²+8mn+3n² 10x²-21xy+2y²
答
3a²-7a-6=(3a+2)(a-3)
6x²-11xy+3y² =(3x-y)(2x-3y)
4m²+8mn+3n² =(2m+3n)(2m+n)
10x²-21xy+2y²=(10x-y)(x-2y)十字相乘怎么做的呀。。这就是十字相乘做的啊