2a^2-b^2-[(3a^2-4b^2)-(1/2a-b)]

问题描述:

2a^2-b^2-[(3a^2-4b^2)-(1/2a-b)]

2a^2-b^2-[(3a^2-4b^2)-(1/2a-b)]
=2a²-b²-(3a²-4b²-1/2a+b)
=2a²-b²-3a²+4b²+1/2a-b
=-a²+3b²+1/2a-b