(a) Find the term independent of $x$ in the expansion of $\left(x + \dfrac{2}{x}\right)^6$. (6 marks) (b) Write down the expansion of $(1 + x)^{-1}$ in ascending powers of $x$ up to and including the term in $x^3$, and state the range of values of $x$ for which it is valid. (4 marks) (c) Expand $(1 - 3x)^{\frac{1}{2}}$ in ascending powers of $x$ up to and including the term in $x^2$. (5 marks)