Let \[\mathrm{D}\] be the domain of the function \[f(x)=\sin ^{-1}\left(\log _{3 x}\left(\frac{6+2 \log _{3} x}{-5 x}\right)\right)\]. If the range of the function \[\mathrm{g}: \mathrm{D} \rightarrow \mathbb{R}\] defined by \[\mathrm{g}(x)=x-[x],([x]\] is the greatest integer function), is \[(\alpha, \beta)\], then \[\alpha^{2}+\frac{5}{\beta}\] is equal to
Solutions · 1
Official solution
First, the function f(x)=sin−1(log3x(−5x6+2log3x)) has several restrictions :
Since the arcsine function sin−1(x) is only defined for −1≤x≤1, this means that log3x(−5x6+2log3x) must be between -1 and 1.
For the logarithm to be defined, 3x>0⇒x>0 .......(1)
because the base of a logarithm must be greater than 0 and not equal to 1. Also, x=31 .......(2)
as the base cannot be 1.
Moreover, the inner function of the logarithm −5x6+2log3x must be greater than 0.
\[ \Rightarrow \] 6+2log3x0)