b) 33^3-8⋮31
=33^3-2^3
=33-2=31
mà 31⋮31
⇒33^2-8⋮31
b)\(33^3-8\)
\(=33^3-2^3\)
\(=\left(33-2\right)\left(33^2+2.33+2^2\right)\)
\(=31\left(33^2+70\right)\) chia hết cho 31
c: \(33^{33}-8\)
\(=\left(33^{11}\right)^3-2^3\)
\(=\left(33^{11}-2\right)\left(33^{22}+2\cdot33^{11}+4\right)\) là hợp số