Comparison of surds.
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(a) If a and b are surds of the same order, say n, then \(\sqrt[n]{a}\) > \(\sqrt[n]{b}\) if a > b.
For example, \(\sqrt[5]{27}\) > \(\sqrt[5]{20}\) as 27 > 20.
(b) If the given surds are not of the same order, then first convert them to surds of the same order and then compare. For example, to compare \(\sqrt[3]{2}\) and \(\sqrt[4]{3}\), we take the LCM of the orders, i.e., 3 and 4, i.e., 12.
Now, \(\sqrt[3]{2}\) = \(\sqrt[12]{2^4}\) = \(\sqrt[12]{16}\) (∴ \(\sqrt[3]{2}\) = \(2^\frac{1}{3}\) = \(2^\frac{4}{12}\))
\(\sqrt[4]{3}\) = \(\sqrt[12]{3^3}\) = \(\sqrt[12]{27}\) (∴ \(\sqrt[4]{3}\) = \(3^\frac{1}{4}\) = \(3^\frac{3}{12}\))
Since, 27 > 16, therefore, \(\sqrt[12]{27}\) > \(\sqrt[12]{16}\), i.e, \(\sqrt[4]{3}\) > \(\sqrt[3]{2}\).