1) Ta có: \(3^{x+1}+3^{x+2}=324\)
\(\Leftrightarrow3^x\cdot3+3^x\cdot9=324\)
\(\Leftrightarrow3^x\left(3+9\right)=324\)
\(\Leftrightarrow3^x=27\)
hay \(3^x=3^3\)
⇔x=3
Vậy: x=3
2) Ta có: \(10-3\left(x-1\right)=-5\)
\(\Leftrightarrow10-3x+3+5=0\)
\(\Leftrightarrow18-3x=0\)
\(\Leftrightarrow3x=18\)
hay x=6
Vậy: x=6
3) Ta có: \(-12-\left|5-x\right|=-14\)
\(\Leftrightarrow\left|5-x\right|=-12+14=2\)
\(\Leftrightarrow\left[{}\begin{matrix}5-x=2\\5-x=-2\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=3\\x=7\end{matrix}\right.\)
Vậy: \(x\in\left\{3;7\right\}\)
