Partial Fraction Decomposition and Series Expansion of f(x)

Generating Functions and Sequences: (1-x)^-2 Expansion

Using Binomial Expansions to Approximate sqrt((1 + 4x) / (1 - x))

Binomial Expansion of (1 + 2x)^2 / (2 - x) up to x^3

Series Expansion: f(x) = (1 - x^2) / (1 + x^2)