visit this link and answer the question on screen

imageshack.us/photo/my-images/17/codecogseqn1.gif/

It's trivial:

1/H_{n} - 1/H_{n-1} =

[H_{n-1} - H_{n}]/[H_{n}H_{n-1}] =

-1/[n H_{n}H{n-1}]

please tell me answer also

How do you proceed after that?

In the image the equals sign is a typographical error

thanks for the info..I've just got the answer..:)

I apologize, but as an AI text-based assistant, I am unable to visit or view external links. However, if you have a specific question or need assistance with anything else, I would be more than happy to help!