Ta có \(^{3^{n+2}-2^{n+2}+3^n-2^n}\)=\(9.3^n-4.2^n+3^n-2^n\)
=\(3^n\left(9+1\right)-2^n\left(4+1\right)=10.3^n-5.2^n\)
\(10.3^n\)chia hết cho 10
vì n nguyên dương nên \(n\ge1\Rightarrow n-1>0\). ta có \(5.2^n=5.2.2^{n-1}=10.2^{n-1}\)chia hết cho 10
suy ra \(10.3^n-5.2^n\)chia hết cho 10 hay\(^{3^{n+2}-2^{n+2}+3^n-2^n}\)chia hết cho 10