If ${a^x} = bc,{b^y} = ca,\,{c^z} = ab,$ then $xyz$=
$0$
$1$
$x + y + z$
$x + y + z + 2$
If ${a^{1/x}} = {b^{1/y}} = {c^{1/z}}$ and ${b^2} = ac$ then $x + z = $
${a^{m{{\log }_a}n}} = $
The number of integers $q , 1 \leq q \leq 2021$, such that $\sqrt{ q }$ is rational, and $\frac{1}{ q }$ has a terminating decimal expansion, is
Solution of the equation ${4.9^{x - 1}} = 3\sqrt {({2^{2x + 1}})} $ has the solution
$\sqrt {(3 + \sqrt 5 )} $ is equal to