\(2020^{\left(n-20\right).\left(n+11\right)}=1\)
\(\Leftrightarrow\left(n-20\right)\left(n+11\right)=0\)
\(\Leftrightarrow\orbr{\begin{cases}n-20=0\\n+11=0\end{cases}\Leftrightarrow\orbr{\begin{cases}n=20\\n=-11\left(loai\right)\end{cases}}}\)
Vây n=20