- a. Find the first four terms, in ascending powers of \(x\), of the binomial expansion of
$$\left( \frac { 1 } { 9 } - 2 x \right) ^ { \frac { 1 } { 2 } }$$
giving each coefficient in its simplest form.
b. Explain how you could use \(x = \frac { 1 } { 36 }\) in the expansion to find an approximation for \(\sqrt { 2 }\).
There is no need to carry out the calculation.