- (a) Find the first 4 terms, in ascending powers of \(x\), of the binomial expansion of
$$\left( 1 + \frac { x } { 3 } \right) ^ { 18 }$$
giving each term in its simplest form.
(b) Use the answer to part (a) to find an estimated value for \(\left( \frac { 31 } { 30 } \right) ^ { 18 }\), stating the value of \(x\) that you have used and showing your working. Give your estimate to 4 decimal places.
II