\(=2^{21}-2^{18}=2^{18}\left(2^3-1\right)=2^{17}.2.7=2^{17}.14\)
\(8^7=\left(2^3\right)^7=2^{21}\)
\(\Rightarrow8^7-2^{18}=2^{21}-2^{18}=2^{18}\times\left(2^3-1\right)=2^{18}\times7\)
\(=2^{17}\times2\times7=2^{17}\times14⋮14\)
Vậy \(8^7-2^{18}⋮14\)
Ta có :8^7 - 2^18
= (2^3)^7 - 2^18
= 2^21 - 2^18
= 2^17 . ( 2^4 - 2 )
= 2^17 . ( 16 - 2 )
= 2^17 . 14
=> đpcm
Ta có : \(8^7-2^{18}=\left(2^3\right)^7-2^{18}=2^{21}-2^{18}\)
\(=2^{18}.2^3-2^{18}=2^{18}.\left(2^3-1\right)\)
\(=2^{18}.7=\left(2^{17}.14\right)⋮14\)
\(\Rightarrow\) \(\left(8^7-2^{18}\right)⋮14\)
