a, \(x^{15}=x\)
\(\Rightarrow\orbr{\begin{cases}x=1\\x=0\end{cases}}\)
b, \(\left(2x+1\right)^3=125\)
\(\Rightarrow\left(2x+1\right)^3=5^3\)
\(\Rightarrow\) \(2x+1=5\)
\(\Rightarrow\) \(2x=5-1\)
\(\Rightarrow\) \(2x=4\)
\(\Rightarrow\) \(x=4:2\)
\(\Rightarrow\) \(x=2\)
c, \(\left(x-5\right)^4=\left(x+5\right)^6\)
\(\Rightarrow\orbr{\begin{cases}x-5=0\\x-5=1\end{cases}}\)
\(\Rightarrow\orbr{\begin{cases}x=5\\x=6\end{cases}}\)