Ta thấy \(11^{n+2}+12^{2n+1}+12^2=121.11^n+12.12^{2n}+144\)
\(=\left(133-12\right).11^n+12.144^n+144\)
\(=133.11^n+133-12.11^n+12.144^n+11\)
\(=133\left(11^n+1\right)-12\left(144^n-11^n\right)+11\)
Ta thấy \(133\left(11^n+1\right)⋮133\) ; \(144^n-11^n⋮\left(144-11\right)\Rightarrow144^n-11^n⋮133\)
Vậy nên \(11^{n+2}+12^{2n+1}+12^2\) chia 133 dư 11.