解
(5a²-3b)-3(a²-2b)
=5a²-3b-3a²+6b
=(5a²-3a²)+(6b-3b)
=2a²+2b去括号。我有去括号啊解(5a²-3b)-3(a²-2b)=5a²-3b-3a²+6b——却括号=(5a²-3a²)+(6b-3b)——合并同类项=2a²+2b