5a²+[a²+(5a²-2a)-2(a²-3a)],其中a=-1/2.

问题描述:

5a²+[a²+(5a²-2a)-2(a²-3a)],其中a=-1/2.
求解求解,大神求解,拜托拜托.

=5*¼+【¼+(5/4+1)-2(¼+3/2)】
=5/4+(¼+9/4)-2*7/4
=5/4+10/4-14/4
=1/4