Which is rational?

Which is rational?
  1. $\sqrt{2} \cdot \sqrt{8}$
  2. $\sqrt{2} + \sqrt{3}$
  3. $2 + \sqrt{5}$
  4. $\sqrt{7}$

Solution

$\sqrt{2 \cdot 8} = \sqrt{16} = 4$, rational.

Asked in: MH-SSC-9

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