Question

Cho Phép bằng 2+2 mu2+mu3+2mu4+2mu5+2mu6+2mu7+2mu8+2mu9+2mu10.Chung minh P chia hết cho 3

Lam on giúp mik voi

Answer 1

P =2+2^2+2^3+2^4+2^5+2^6+2^7+2^8+2^9+2^10  

    = ( 2+2^2 ) + ( 2^3 + 2^4 ) + ( 2^5 + 2^6 ) + ( 2^7 + 2^8 ) + ( 2^9 + 2^10 )

   = 2.( 1+2 ) + 2^3.( 1+2 ) + 2^5.( 1+2 ) + 2^7.( 1+2 ) + 2^9.( 1 + 2 )

   = 2.3+2^3.3+2^5.3+2^7.3+2^9.3

   = ( 2+2^3+2^5+2^7+2^9).3 chia hết cho 3

=> P chia hết cho 3