To prove `1/sqrt(1)+1/sqrt(2)+1/sqrt(3)+1/sqrt(4)+........1/sqrt(n)>sqrt(n)`
n`>=2`
For n=2, `1/sqrt(1)+1/sqrt(2)~~1.707`
`sqrt(2)~~1.414`
`:. 1/sqrt(1)+1/sqrt(2)>sqrt(2)`
Let's assume that for k> 2 , `1/sqrt(1)+1/sqrt(2)+1/sqrt(3)+.....+1/sqrt(k)>sqrt(k)`
So, `1/sqrt(1)+1/sqrt(2)+1/sqrt(3)+....+1/sqrt(k)+1/sqrt(k+1)>1/sqrt(k+1)`
or let's show that `sqrt(k)+1/sqrt(k+1)>sqrt(k+1)` ,k>2
Multiply the above inequality by `sqrt(k+1)`
`sqrt(k)sqrt(k+1)+1>(k+1)`
Rewriting the above inequality as below; shows that the above is true ,
`sqrt(k)sqrt(k+1)+1>sqrt(k)sqrt(k)+1`
`:. 1/sqrt(1)+1/sqrt(2)+1/sqrt(3)+......+1/sqrt(k)+1/sqrt(k+1)>sqrt(k+1)`
By the extended mathematical induction, the inequality is valid for all n,n`>=2`
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