#9 ^ x = x
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This equation has no real solution
Define $f(x) := 9^x - x$, then $f'(x) = \ln(9) \cdot 9^x - 1$.
ℝafain
Hence
$$f'(x)
\begin{cases}
<0&\text{ if }x<-\frac{\ln(\ln(9))}{\ln(9)}\
=0&\text{ if }x=-\frac{\ln(\ln(9))}{\ln(9)}\
0&\text{ if }x=-\frac{\ln(\ln(9))}{\ln(9)}
\end{cases}$$
ℝafain
Hence $f$ is minimum at $-\frac{\ln(\ln(9))}{\ln(9)}$, where its value is $\frac{1+\ln(\ln(9))}{\ln(9)} > 0$.
ℝafain
Hence $f$ does not attain zero anywhere in $\mathbb R$.
ℝafain