If ${a^x} = {b^y} = {(ab)^{xy}},$ then $x + y = $
$0$
$1$
$xy$
None of these
The greatest number among $\root 3 \of 9 ,\root 4 \of {11} ,\root 6 \of {17} $ is
If ${\left( {{2 \over 3}} \right)^{x + 2}} = {\left( {{3 \over 2}} \right)^{2 - 2x}},$then $x =$
If $x + \sqrt {({x^2} + 1)} = a,$ then $x =$
${{{{2.3}^{n + 1}} + {{7.3}^{n - 1}}} \over {{3^{n + 2}} - 2{{(1/3)}^{l - n}}}} = $
$\root 4 \of {(17 + 12\sqrt 2 )} = $