Expanding a formula

[Pattielli]

Can you tell me what the following formula will be after it gets expanded ?
(1+x+x^2+.......+x^n^-^2+x^n^-^1)^2 = ?

Thanks a lot,

[Muzza]

What's written inside the parantheses is a geometric series. It's equal to (1 - x^(n - 1 + 1)) / (1 - x). Now just square it...

[Pattielli]

Thanks a lot,