Rationalise the denominator of $\frac{11}{\sqrt{5}}$. Give your answer in its simplest form.
The objective is to rationalize the denominator of the fraction \(\frac{11}{\sqrt{5}}\). Rationalizing a denominator means rewriting a fraction so that the denominator contains only rational numbers. In this case, the denominator is \(\sqrt{5}\), which is an irrational number. The goal is to eliminate the radical from the denominator without changing the overall value of the fraction.
To rationalize the denominator of a fraction in the form \(\frac{a}{\sqrt{b}}\), we multiply both the numerator and the denominator by \(\sqrt{b}\). By the property of fractions, multiplying by \(\frac{\sqrt{b}}{\sqrt{b}}\) is equivalent to multiplying by \(1\), so the value of the expression remains unchanged. In our case, we multiply by \(\frac{\sqrt{5}}{\sqrt{5}}\):
\[\frac{11}{\sqrt{5}} \times \frac{\sqrt{5}}{\sqrt{5}} = \frac{11 \times \sqrt{5}}{\sqrt{5} \times \sqrt{5}}.\]
Now we perform the multiplication in the numerator and the denominator. The numerator becomes \(11\sqrt{5}\). In the denominator, \(\sqrt{5} \times \sqrt{5} = 5\). Substituting these values back into our expression, we get:
\[\frac{11\sqrt{5}}{5}.\]
We check for further simplification by seeing if \(11\) and \(5\) have common factors. Since both are prime numbers and \(11\) is not divisible by \(5\), the fraction is already in its simplest form.
In construction or engineering, you might encounter measurements that involve square roots, such as calculating the diagonal of a square plot of land. If a calculation results in a measurement like \(\frac{11}{\sqrt{5}}\) meters, it is often more practical to rationalize the denominator to get \(\frac{11\sqrt{5}}{5}\) meters. This makes it easier to estimate the numerical value using the approximation \(\sqrt{5} \approx 2.236\), allowing for clearer communication of the required dimensions.