The equation $\sqrt {(x + 1)} - \sqrt {(x - 1)} = \sqrt {(4x - 1)} $, $x \in R$ has
One solution
Two solution
Four solution
No solution
${{{{2.3}^{n + 1}} + {{7.3}^{n - 1}}} \over {{3^{n + 2}} - 2{{(1/3)}^{l - 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
$\sqrt {(3 + \sqrt 5 )} $ is equal to
${4 \over {1 + \sqrt 2 - \sqrt 3 }} = $
The cube root of $9\sqrt 3 + 11\sqrt 2 $ is