Answer :
[tex] \log (x-9) = 1 - \log x \\
D:x-9>0 \wedge x>0\\
D: x>9 \wedge x>0\\
D:x>9\\
\log(x-9)+\log x=1\\
\log x(x-9)=1\\
10^1=x^2-9x\\
x^2-9x-10=0\\
x^2+x-10x-10=0\\
x(x+1)-10(x+1)=0\\
(x-10)(x+1)=0\\
x=10 \vee x=-1\\
-1\not \in D \Rightarrow x=10
[/tex]
