2(a+b)+3a(a+b)=()(a+b)-(x-y)的平方-(x-y)=-(x-y)()ab-ac+b-c3a-9b+2ac-6bc

问题描述:

2(a+b)+3a(a+b)=()(a+b)
-(x-y)的平方-(x-y)=-(x-y)()
ab-ac+b-c
3a-9b+2ac-6bc