The number ${\log _2}7$ is
An integer
A rational number
An irrational number
A prime number
The sum of all the natural numbers for which $log_{(4-x)}(x^2 -14x + 45)$ is defined is -
If ${\log _{\tan {{30}^ \circ }}}\left( {\frac{{2{{\left| z \right|}^2} + 2\left| z \right| - 3}}{{\left| z \right| + 1}}} \right)\, < \, - 2$ then
Which is the correct order for a given number $\alpha $in increasing order
If ${\log _{10}}3 = 0.477$, the number of digits in ${3^{40}}$ is
If ${\log _5}a.{\log _a}x = 2,$then $x$ is equal to