Question

tell me answer in details

Answer 1

Hi...☺

Here is your answer...✌

$\sqrt{13 - x \sqrt{10} } = \sqrt{8} + \sqrt{5} \\ \\ squaring \: both \: sides \\ we \: get \\ \\ 13 - x \sqrt{10} = ( \sqrt{8} + \sqrt{5} ) {}^{2} \\ \\ 13 - x \sqrt{10} = ( \sqrt{8} ) {}^{2} + ( \sqrt{5} ) {}^{2} + 2 \times \sqrt{8} \times \sqrt{5} \\ \\ 13 - x \sqrt{10} = 8 + 5 + 2 \sqrt{40} \\ \\ 13 - x \sqrt{10} = 13 + 2 \times 2 \sqrt{10} \\ \\ - x \sqrt{10} = 4 \sqrt{10} \\ \\ - x = 4 \\ \\ = > x = - 4$

Hence,

Option (C) -4 is the correct answer