Find the first 4 terms, in ascending powers of xxx, of the binomial expansion of
(3−x9)9 \left(3 - \frac{x}{9}\right)^9 (3−9x)9giving each term in its simplest form.
Hence find the constant term in the series expansion of
(2+1x)2(3−x9)9 \left(2 + \frac{1}{x}\right)^2 \left(3 - \frac{x}{9}\right)^9 (2+x1)2(3−9x)9
