先化简在求值｛（a+1/2b)²+(a-1/2b)²｝*（2a²-1/2b²）其中a=-3 b=4

先化简在求值｛（a+1/2b)²+(a-1/2b)²｝*（2a²-1/2b²）其中a=-3 b=4

原式=(a²+ab+1/4b²+a²-ab+1/4b²)*(2a²-1/2b²)
=(2a²+1/2b²)(2a²-1/2b²)
=4a^4-1/4b^4
=4*81-1/4*256
=324-64
=260