2010-03-05 16:31:09 +0800 #1
先化简，再求值：[（a^2 - b^2)/(a^2 x b-ab^2)] / [1+ (a^2 + b^2)/2ab],其中a=5,b=-3
2010-03-05 16:31:09 +0800 #2
答案1。你还初中生吧，初几了啊
2010-03-05 16:31:09 +0800 #3
(a^2 - b^2)/(a^2 x b-ab^2)=(a+b)(a-b)/ab(a-b)=(a+b)/ab
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2010-03-05 16:31:09 +0800 #4
1+ (a²+b²)/2ab=(a²+2ab+b²)/2ab=(a+b)²/2ab
[(a+b)/ab]/[(a+b)²/2ab]=(a+b)/ab * 2ab/(a+b)²=2/(a+b)
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[(a+b)/ab]/[(a+b)²/2ab]=(a+b)/ab * 2ab/(a+b)²=2/(a+b)
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