(a+1)^2-2(a+1)(a-1)+3(a-1)^2
5个回答

直接解(a+1)^2-2(a+1)(a-1)+3(a-1)^2

=a^2+2a+1-2a^2+2+3a^2-6a+3

=2a^2-4a+6

较简便的(a+1)^2-2(a+1)(a-1)+3(a-1)^2

=[(a+1)-(a-1)]^2+2(a-1)^2

=4+2a^2-4a+2

=2a^2-4a+6

我本助人为乐而解,这里省了几步,我一般都会这样写,不知你能看懂吗