This expression is derived from the binomial expansion of \( \left( \frac{(1 + x)}{(n + 1)} \right)' \). The right-hand side represents the binomial series expansion of \( (1 + x)^{n+1} \).
Each coefficient \( n_k \) is a binomial coefficient pertinent to the expansion. The expansion of \( \left( \frac{(1 + x)}{(n + 1)} \right) \) yields terms such as:
- The initial term, \( n_0 x \), equals \( x \).
- The subsequent term is \( n_1 \frac{x^2}{2} \), which simplifies to \( \frac{x^2}{2} \), and so forth.
The general term in this expansion is \( n_k \frac{x^k}{k+1} \), where \( n_k \) denotes binomial coefficients.
This expansion facilitates approximation of \( \left( 1 + x \right)^{n+1} \) for small \( x \) values.