- (a) Find the first 4 terms, in ascending powers of \(x\), of the binomial expansion of
$$\left( \frac { 1 } { 4 } - 5 x \right) ^ { \frac { 1 } { 2 } } \quad | x | < \frac { 1 } { 20 }$$
giving each coefficient in its simplest form.
By substituting \(x = \frac { 1 } { 100 }\) into the answer for (a),
(b) find an approximation for \(\sqrt { 5 }\)
Give your answer in the form \(\frac { a } { b }\) where \(a\) and \(b\) are integers to be found.