2/(a-2)+(a²-4a+4)/(a²-1)÷(a-2)/(a+1)·····

问题描述:

2/(a-2)+(a²-4a+4)/(a²-1)÷(a-2)/(a+1)·····
先化简再求值:2/(a-2)+(a²-4a+4)/(a²-1)÷(a-2)/(a+1)其中a=1+根号2

2/(a-2)+(a²-4a+4)/(a²-1)÷(a-2)/(a+1)=2/(a-2)+(a-2)²/([(a+1)(a-1)]×(a+1)/(a-2)=2/(a-2)+(a-2)/(a-1)=[2(a-1)+(a-2)²]/[(a-2)(a-1)]=[2(1+√2-1)+(1+√2-2)]/[(1+√2-2)(1+√2-1)]={√2-1...这个额·····答案是错的,我刚刚算了一遍得出的结果不是这个不可能呀,你再看看!我又算了一遍,不知为啥得出的结果是2·······我也算了一遍,没错呀!,你看看我算的,哪里错了?我得出的答案是(2+根号2)/2能把你做的过程打出来吗?字数太多了不能打出来,还有我刚刚打错了,结果是3(2+根号2)/2你错的地方是[2(1+√2-1)+(1+√2-2)]/[(1+√2-2)(1+√2-1)]我在这算出了3/(2-根号2)=[2(1+√2-1)+(1+√2-2)²]/[(1+√2-2)(1+√2-1)]=[2√2+(√2-1)²]/[√2(√2-2)]=(2√2+3-2√2]/(4-2√2)=3/[2(2-√2)]=3(2+√2)/[2×(4-2)]=3(2+√2)/4其实[(1+√2-2)(1+√2-1)]=(根号2-1)根号2。来着不过我已经把答案得出了,谢谢