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　　【llllllllllllllllllllllllllllllllllllllllllllllllll(298:41:46)1.已知a≥1,比较M=√（a+1）-√a与N=√a-√（a-1）的大小. 2.比较2a2+3和4a的大小.】

　　llllllllllllllllllllllllllllllllllllllllllllllllll(298:41:46)

　　1.已知a≥1,比较M=√（a+1）-√a与N=√a-√（a-1）的大小.

　　2.比较2a2+3和4a的大小.

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2020-03-2418:58

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马宏发

　　以下以（）^0.5代替开方,以（）^2代替平方.第一道题：首先,M>0,N>0;其次M^2-N^2=(a+1+a-2*(a*(a+1))^0.5)-(a+1+a-2*(a*(a-1))^0.5)=2*(a*(a-1))^0.5-2*(a*(a+1))^0.5,显然小于零,故而M0所以应该是2a^2+3>4a...

2020-03-24 19:01:36

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