a.
\(\left(\frac{1}{3}\right)^{2x-1}=243\)
\(\left(\frac{1}{3}\right)^{2x-1}=\left(\frac{1}{3}\right)^{-5}\)
\(2x-1=-5\)
\(2x=-5+1\)
\(2x=-4\)
\(x=-\frac{4}{2}\)
\(x=-2\)
b.
\(\left(0,125\right)^{x+1}=64\)
\(\left(0,125\right)^{x+1}=\left(0,125\right)^{-2}\)
\(x+1=-2\)
\(x=-2-1\)
\(x=-3\)