Tìm x biết: 1) 100 - (x + 5) = 2^3.5.
Giải thích
Tìm x biết
1/ \[100 - \left( {x + 5} \right) = {2^3}.5\]
\[\begin{array}{l}100 - \left( {x + 5} \right) = {2^3}.5\\{\rm{ }}\left( {x + 5} \right) = 100 - 8.5\end{array}\]
\[\begin{array}{l}x + 5 = 100 - 40\\x = 60 - 5\\x = 55\end{array}\]
\[2/{\rm{ }}{5.4^x} + {4^{2 + x}} = 336\]
\[\begin{array}{l}2/{\rm{ }}{5.4^x} + {4^{2 + x}} = 336\\{\rm{ }}{{\rm{4}}^x}\left( {5 + {4^2}} \right) = 336\end{array}\]
\[\begin{array}{l}{\rm{ }}{{\rm{4}}^x} = 16\\{\rm{ }}{{\rm{4}}^x} = {4^2}\\{\rm{ }}x = 2\end{array}\]