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A square deal (Posted on 2022-07-18) Difficulty: 2 of 5
Find the sum of:

  1       1       1               1
----- + ----- + ----- + ... + ----------
√1+√2   √2+√3   √3+√4         √999+√1000

No Solution Yet Submitted by Ady TZIDON    
Rating: 3.0000 (1 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Solution computer solution | Comment 2 of 4 |
The sum is one less than the square root of 1000.

This table illustrates the relationship

       9   2.16227766016837952278706325      10.0000000000000000000000
      99   9.00000000000000000000000000     100.0000000000000000000000
     999  30.62277660168379256333537342    1000.0000000000000000000000
    9999  99.00000000000000000000000000   10000.0000000000000000000000
   99999 315.22776601683796116049052216  100000.0000000000000000000000
   
The last odd integer under the radical is in column 1 (column 3 is the last even integer, under the last radical, though programmed as the square of the sum incremented by 1).  The middle column is the sum, which is 1 lower than the square root of the last column.

from

clc
for l=1:5
t=0;
for i0=10^l-1:-1:1
  i=vpa(i0);
  t=t+(1/(sqrt(i)+sqrt(i+1)));  
end

fprintf('%8d %30.26f %30.22f\n',10^l-1, t, (t+1)^2)
end

  Posted by Charlie on 2022-07-18 08:33:49
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