If \(b\) is very small as compared to the value of \(a\), so that the cube and other higher powers of \(\frac{b}{a}\) ca…

If \(b\) is very small as compared to the value of \(a\), so that the cube and other higher powers of \(\frac{b}{a}\) can be neglected in the identity \(\frac{1}{a-b}+\frac{1}{a-2 b}+\frac{1}{a-3 b}+\ldots+\frac{1}{a-n b}=\alpha n+\beta n^2+\gamma n^3\), then the value of \(\gamma\) is.

[JEE Main 2021, 25 Jul (Shift 1)]