The value of $\sqrt {[12 - \sqrt {(68 + 48\sqrt 2 )} ]} = $
$2 + \sqrt 2 $
$2 - \sqrt 2 $
$\sqrt 2 - 1$
None of these
${4 \over {1 + \sqrt 2 - \sqrt 3 }} = $
If $x = \sqrt 7 + \sqrt 3 $ and $xy = 4,$then ${x^4} + {y^4}=$
${{\sqrt {6 + 2\sqrt 3 + 2\sqrt 2 + 2\sqrt 6 } - 1} \over {\sqrt {5 + 2\sqrt 6 } }}$
$\sqrt {(3 + \sqrt 5 )} - \sqrt {(2 + \sqrt 3 )} = $
If ${x^y} = {y^x},$then ${(x/y)^{(x/y)}} = {x^{(x/y) - k}},$ where $k = $