\(\Leftrightarrow3.\left(\frac{16}{36}\right)^x+2.\left(\frac{81}{36}\right)^x=5\)
\(\Leftrightarrow3\left(\frac{4}{9}\right)^x+2.\left(\frac{9}{4}\right)^x-5=0\)
Đặt \(\left(\frac{4}{9}\right)^x=a>0\) phương trình trở thành:
\(3a+\frac{2}{a}-5=0\Leftrightarrow3a^2-5a+2=0\Rightarrow\left[{}\begin{matrix}a=1\\a=\frac{2}{3}\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}\left(\frac{4}{9}\right)^x=1\\\left(\frac{4}{9}\right)^x=\frac{2}{3}\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=0\\x=\frac{1}{2}\end{matrix}\right.\)
