\(\left|2x-1\right|=5\)
\(\Leftrightarrow\left[\begin{matrix}2x-1=5\\2x-1=-5\end{matrix}\right.\Leftrightarrow\left[\begin{matrix}2x=6\\2x=-4\end{matrix}\right.\Leftrightarrow\left[\begin{matrix}x=3\\x=-2\end{matrix}\right.\)
Vậy ...
b ) Đề sai rồi :)
a/\(\left|2x-1\right|=5\)
\(\Rightarrow\left[\begin{matrix}2x-1=5\\2x-1=-5\end{matrix}\right.\)
\(\Rightarrow\left[\begin{matrix}2x=5+1\\2x=-5+1\end{matrix}\right.\)
\(\Rightarrow\left[\begin{matrix}2x=6\\2x=-4\end{matrix}\right.\)
\(\Rightarrow\left[\begin{matrix}x=6:2\\x=-4:2\end{matrix}\right.\)
\(\Rightarrow\left[\begin{matrix}x=3\\x=-2\end{matrix}\right.\)
b/\(\left(5^x-1\right).3-2=70\)
\(\left(5^x-1\right).3=70+2\)
\(\left(5^x-1\right).3=72\)
\(5^x-1=72:3\)
\(5^x-1=24\)
\(5^x=24+1\)
\(5^x=25\)
\(5^x=5^2\)
\(\Rightarrow x=2\)