Cho hai số dương a, b thỏa mãn \(\left\{ \begin{ar...

B

- Hướng dẫn giải

\(\begin{array}{l}\left\{ \begin{array}{l}{\log _4}a + {\log _2}{b^2} = 3\\{\log _4}{a^2} + {\log _2}b = 9\end{array} \right.\\ \Rightarrow \left\{ \begin{array}{l}{\log _4}a + 2{\log _2}b = 3\\2{\log _4}a + {\log _2}b = 9\end{array} \right.\\ \Rightarrow \left\{ \begin{array}{l}{\log _4}a = 5\\{\log _2}b = - 1\end{array} \right.\\ \Rightarrow \left\{ \begin{array}{l}a = {4^5}\\b = {2^{ - 1}}\end{array} \right.\\ \Rightarrow a + 2b = {4^5} + 1 = {2^{10}} + 1\end{array}\)