A=2 + 22 + 23 + 24 + ......+ 2100
A=(2 + 22) + (23 + 24) + ......+ (299 + 2100)
A=2 . (1+2) + 23 . (1+2) + ....+ 299 . (1+2)
A=2 .3 + 23 . 3 + ....+ 299 . 3
A=3 . (2 + 23 + .. + 299)
=> A chia hết cho 3
A=2 + 22 + 23 + 24 + ......+ 2100
A=(2 + 22) + (23 + 24) + ......+ (299 + 2100)
A=2 . (1+2) + 23 . (1+2) + ....+ 299 . (1+2)
A=2 .3 + 23 . 3 + ....+ 299 . 3
A=3 . (2 + 23 + .. + 299)
=> A chia hết cho 3
A= 2+2^2+2^3+2^4+...+2^100
= 2(1+2)+2^3(1+2)+...+2^99(1+2)
= 2.3+2^3.3+...+2^99.3
Suy ra A chia hết cho 3.
hpuh9h8 uuioooook
Mấy pro giỏi Toán ơiiii, giúp mik vs !!!
@Trần Ngọc Minh
Ok, Thanks bạn nhiều, mik t ic k cho r nhé
HT
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