If ${a^x} = bc,{b^y} = ca,\,{c^z} = ab,$ then $xyz$=
$0$
$1$
$x + y + z$
$x + y + z + 2$
$\sqrt {(3 + \sqrt 5 )} $ is equal to
If ${2^x} = {4^y} = {8^z}$ and $xyz = 288,$ then ${1 \over {2x}} + {1 \over {4y}} + {1 \over {8z}} = $
Solution of the equation ${4.9^{x - 1}} = 3\sqrt {({2^{2x + 1}})} $ has the solution
The value of ${{15} \over {\sqrt {10} + \sqrt {20} + \sqrt {40} - \sqrt 5 - \sqrt {80} }}$ is
${a^{m{{\log }_a}n}} = $