Question

 

(3x - 8 ) mũ 10= 3x-8 mũ2

243 <= 3 mũ 2x-1<=3 mũ 8

 

Answer 1

\(\left(3x-8\right)^{10}=\left(3x-8\right)^2\\ \Rightarrow\left(3x-8\right)^{10}-\left(3x-8\right)^2=0\\ \Rightarrow\left(3x-8\right)^2\left[\left(3x-8\right)^8-1\right]=0\\ \Rightarrow\left[{}\begin{matrix}\left(3x-8\right)^2=0\\\left(3x-8\right)^8=1\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}3x-8=0\\3x-8=1\\3x-8=-1\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=\dfrac{8}{3}\\x=3\\x=\dfrac{7}{3}\end{matrix}\right.\)

\(243\le3^{2x-1}\le3^8\\ \Rightarrow3^5\le3^{2x-1}\le3^8\\ \Rightarrow2x-1\in\left\{5;6;7;8\right\}\\ \Rightarrow x\in\left\{3;\dfrac{7}{2};4;\dfrac{9}{2}\right\}\)