Chứng minh rằng:81^7-27^9+3^29 chia hết cho 33

${81}^7-{27}^9+3^{29}⋮33$ 

Ta có: ${81}^7-{27}^9+3^{29}={\left(3^4\right)}^7-{\left(3^3\right)}^9+3^{29}=3^{28}-3^{27}+3^{29}=3^{26}\cdot \left(3^2-2+3^3\right)=3^{26}.33⋮33.$ 

Vậy ${81}^7-{27}^9+3^{29}⋮33$