有理数ab定义:a*b=3a+2b.则[(x+y)*(x-y)]*3x.怎么化简?

问题描述:

有理数ab定义:a*b=3a+2b.则[(x+y)*(x-y)]*3x.怎么化简?

[(x+y)*(x-y)]*3x
=[3(x+y)+2(x-y)]*3x
=(5x+y)*3x
=3(5x+y)+2*3x
=21x+3y