a : X= 2 , b : X = 6, c: X = 0 hoặc 1,d:x = 1
a) \(2\cdot5^x=50\)
\(\Leftrightarrow5^x=25\)
\(\Leftrightarrow5^x=5^2\)
\(\Leftrightarrow x=2\)
b) \(3^x:81=9\)
\(\Leftrightarrow3^x=729\)
\(\Leftrightarrow3^x=3^6\)
\(\Leftrightarrow x=6\)
c) \(x=x^{20}\Rightarrow\orbr{\begin{cases}x=0\\x=1\end{cases}}\)
d) \(\left(2x-1\right)^3=\left(2x-1\right)^4\)
\(\Leftrightarrow\left(2x-1\right)^3-\left(2x-1\right)^4=0\)
\(\Leftrightarrow\left(2x-1\right)^3\left(1-2x-1\right)=0\)
\(\Leftrightarrow-2x\left(2x-1\right)=0\)
\(\Rightarrow\orbr{\begin{cases}-2x=0\\2x-1=0\end{cases}\Rightarrow\orbr{\begin{cases}x=0\\x=\frac{1}{2}\end{cases}}}\)
