I What is this one's definite integral ?

This is too far behind me ( time-wise ), and I've gotten different answers from virtually every different online integral calculator . What is the integral of : ( 2.12068539072 x 10^-11 ) / x^2 from 6,378,100 to 1,500,000,000 ? Please only help if you really know your maths well .

 

I just reposted this question cos I thought it didn't take. The integration - as far as I can determine comes to just : -1/x So then I think it gets worked out as
1/b - 1/a where they are ( respectively ) 1500000000 & 6378100 . The answer I get comes to : 1.5678650e-7 - Which I think is wrong.
I'm trying to calculate the average force on an O2 molecule 1,500,000,000 meters out from Earth - coming to ground. It SHOULD also be calculated as from infinity as well. Then I think it should cross check (when its arrival speed is calculated ) with the escape velocity for Earth ( 11.2 Km/s ) .

 

Thank you Erland. - Yes, - I found, - many hours later, the same number that YOU have come up with. I'm going to have a look at that "GNU Octave" you've mentioned. - Once again, - many thanks.

 

- Thank you Delta for you r effort too ! - Also : - No. The answer is the Work done. Then negating that answer, gives the Potential Energy accumulated by that
movement ( out to the greater distance ). - Once again many thanks.

 

Dear Delta,
- I must apologize for my reply to you. I was driving along in the car the next day, and realized how dumb what I wrote was. - You were basically correct, ( except you must negate like I said ) - then dividing by the distance gives the average force, - like you said. - Thanks again.