Question

please explain and gimme correct ans​

Answer 1

Answer:

$a = \frac{1}{ \sqrt{5} - \sqrt{3} } \: \: and \: \: b = \frac{1}{ \sqrt{5} + \sqrt{3} } \\ so \: \: \: a \times b = \frac{1}{ \sqrt{5} - \sqrt{3} } \times \frac{1}{ \sqrt{5 } + \sqrt{3} } \\ = > a \times b = \frac{1}{ { (\sqrt{5}) }^{2} -( { \sqrt{3} )}^{2} } \\ = > a \times b = \frac{1}{(5 - 3)} \\ = > a \times b = \frac{1}{2}$

Step-by-step explanation:

Hence 4th option is correct

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