2(2a²+2ab)-(3a²+4ab-b²）,其中a=2,b=-11/4（a+b）²-6(a-b)+3/4(a+b)²+6(a-b)5（a-b）²-3(a-b)²-7(a-b)-(a-b)²+7(a-b)1/2a²-1/4b+3/2a²-3/4b-a²-5yx²+...