2a-{-3b+【3a-2(3a-b)】},其中a=-1,b=5

问题描述:

2a-{-3b+【3a-2(3a-b)】},其中a=-1,b=5

2a-{-3b+【3a-2(3a-b)】}
=2a+3b-(3a-6a+2b)
=2a+3b+3a-2b
=5a+b