\(27^n.9^n=9^{27}:81\)
\(\Leftrightarrow27^n.9^n=9^{27}:9^2\)
\(\Leftrightarrow3^n=9^{25}\)
\(\Leftrightarrow3^n=\left(3^2\right)^{25}\)
\(\Leftrightarrow3^n=3^{50}\)
\(\Leftrightarrow n=50\left(TM\right)\)
Vậy \(n=50\) là giá trị cần tìm
\(27^n.9^n\) =\(9^{27}:81\)
\(\Leftrightarrow\left(27.9\right)^n=9^{27}.9^2\)
\(\Leftrightarrow243^n=9^{25}\)
\(\Leftrightarrow3^{5n}=3^{50}\)
\(\Rightarrow5n=50\)
\(\Rightarrow n=50:5\)
\(\Rightarrow n=10\)
Vậy số tự nhiên n cần tìm là 10
\(27^n.9^n=9^{27}:81\) \(\Rightarrow\left(27.9\right)^n=9^{27}:9^2\) \(\Rightarrow\left(3^5\right)^n=9^{25}\) \(\Rightarrow\left(3^5\right)^n=\left(3^2\right)^{25}\) \(\Rightarrow3^{5n}=3^{50}\) \(\Rightarrow5n=50\) \(\Rightarrow n=10\) Vậy số tự nhiên n là 10
