流星在舞0511
种子
共回答了18个问题采纳率：88.9% 举报
(1)
f(x)=lnx-(x-1)/sqrt(x)
f'(x)=1/x-(2x-1)/(x*sqrt(x))=(-2x+sqrt(x)+1)/(x*sqrt(x))=0(x≠0)
-2x+sqrt(x)+1=0,t=sqrt(x)(t>0),2t^2-t-1=0,t=1,-1/2(舍)
x=1,在(-∞,1]上函数单调递减,在[1,∞)上函数单调递减,故f(x)单调递减
(2)
f(1)=0-0=0,当x∈(-∞,1]时,y>=0,当x∈[1,∞)时,y1,所以lna-(a-1)/sqrt(a)
1年前
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