Sum of reciprocal of squares <Logic>

[icystrike]

Homework Statement

https://www.physicsforums.com/attachment.php?attachmentid=21977&stc=1&d=1258886072

I think my proof is lousy and may be wrong.
Please help me with it (=
Thanks in advance

Homework Equations

My proof is of below.

The Attempt at a Solution

 

[Mark44]

Homework Statement

https://www.physicsforums.com/attachment.php?attachmentid=21977&stc=1&d=1258886072

What are you trying to prove? The image link above seems to be broken.

I think my proof is lousy and may be wrong.
Please help me with it (=
Thanks in advance

Homework Equations

My proof is of below.

The Attempt at a Solution

 

[icystrike]

thanks mark! I've manage to proof it (+