Question

Please answer.................

Answer 1

LHS =
$\sqrt{13 - x \sqrt{10} }$

squaring it
$13 - x \sqrt{10}$

1................

RHs
$\sqrt{8} + \sqrt{5}$

squaring it

$13 + 4 \sqrt{10}$

2.................

equating 1 and 2

-x = 4

x= -4