chứng minh 2+2^2+2^3+2^4+2^6+2^7+2^8.có chia hết cho -6

2 câu trả lời

2+2^2+2^3+2^4+2^6+2^7+2^8

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

= 2^0 . ( 2 + 2^2 )+ 2^2 . ( 2 + 2^2 ) + 2^4 . ( 2 + 2^2 ) + 2^6 . ( 2 + 2^2 )

= 2^0 . 6 + 2^2 . 6 + 2^4 . 6 + 2^6 . 6

= ( 2^0 + 2^2 + 2^4 + 2^6 ) . 6 

Mà 6 chia hết cho 6

Vậy 2+2^2+2^3+2^4+2^6+2^7+2^8 có chia hết cho 6

xin hay nhất !

2+2^2+2^3+2^4+2^6+2^7+2^8

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

= 2^0 . ( 2 + 2^2 )+ 2^2 . ( 2 + 2^2 ) + 2^4 . ( 2 + 2^2 ) + 2^6 . ( 2 + 2^2 )

= 2^0 . 6 + 2^2 . 6 + 2^4 . 6 + 2^6 . 6

= ( 2^0 + 2^2 + 2^4 + 2^6 ) . 6 

Mà 6 chia hết cho 6

Vậy 2+2^2+2^3+2^4+2^6+2^7+2^8 có chia hết cho 6

XIN HAY NHẤT !