\(\dfrac{4}{1-x}\text{.}\)
\(\dfrac{2}{(1-x)^2}\text{.}\)
\(\dfrac{2x^3}{(1-x)^2}\text{.}\)
\(\dfrac{1}{1-5x}\text{.}\)
\(\dfrac{1}{1+3x}\text{.}\)
\(\dfrac{1}{1-5x^2}\text{.}\)
\(\dfrac{x}{(1-x^3)^2}\text{.}\)