先化简再求值[(a+1/2b)²+(a+1/2b)²](2a²-1/2b²),其

学习时间:2026-04-07 22:46:37 阅读：8644

先化简再求值[(a+1/2b)²+(a+1/2b)²](2a²-1/2b²),其中a=1,b=-2

欣喜的衬衫

2026-04-07 22:46:37

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原式：2*(a+1/2b)² (2a²-1/2b²)后面式子提2出来得：4*(a+1/2b)² (a²-1/4b²)=4*(a+1/2b)²（a+1/2b）(a-1/2b)=4*(a+1/2b)^(a-1/2b)将a=1,b=-2代入,得：27/16