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

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