cho S = 1/ 2^2 + 1/ 3^2 + 1/ 4^2 + 1/5^2 +... + 1/ 2016 ^ 2 . chung to rang S< 1
Chung minh rang: B=1 + 1/2 + 1/3 + 1/4 +1/5 + .....+ 1/22016 - 2 + 1/22016 - 1 > 1008
bai 1 chung minh rang :
2016^2015 + 2016 ^2014 chia het cho -2017
s = 1+3+3^2 + ... +3^118 + 3^119 chia het cho -13 va 41
Cho S=1/3+1/3^2+1/3^3+...+1/3^2015 Chung minh rang s<1/2
em hiểu gì về 2 dạng tồn tai j của tinh thần yêu nước bạn nào biết hướng dẫn mình với
Chung minh rang :
S=1-1/2^2 -1/3^2 -1/4^2-1/5^2-......-1/10^2 >0
Cac ban giup minh giai nhe!
Cho day phan so B=1/2+1/22+1/23+...+1/22016.Chung to rang B<1.
B= 1/2 + 1/22+1/23+...+1/22016
2B= 1+1/2+1/22+...+1/22015
2B-B= (1+1/2+1/22+...+1/22015) - ( 1/2 + 1/22+1/23+...+1/22016)
B = 1 + 1/2 + 1/22 +... + 1/22015 - 1/2 - 1/22 - 1/23 - ... - 1/22016
B= 1 - 1/22016
Suy ra B<1
cho s= 21 + 2 2+ 23+...+2 100
chung to rang
s:3
s :5
s= 21 + 2 2+ 23+...+2 100
S = (2^1 + 2^2 + 2^3 + 2^4) + ...+ ( 2^97+2^98+2^99+2^100)
S= 2( 1+ 2+ 2^2 + 2^3) +...+ 2^97( 1+ 2 + 2^2 + 2^3)
S= 2. 15 +... + 2^97 . 15
S= 15( 2+ 2^5+.... + 2^97)
S= 5.3( 2+ 2^5+.... + 2^97))
=> S chia hết cho 3 và chia hết cho 5
s= 21 + 2 2+ 23+...+2 100
S = (2^1+2^2) + (2^3 + 2^4)+.....+ (2^99 + 2^100)
S = 2(1+2) + 2^3( 1 + 2)+....+2^99( 1+2)
S= 2.3 + 2^3.3 + ...+ 2^99. 3
S = 3( 2+2^3 +...+ 2^99)
=> S chia hết cho 3
1,tim so tn co dang 14xy chiA HET CHO 3VA 5
B, CHO TONG S= 1-3+3^2-3^3+3^4-3^5+..........+3^2014-3^2015
CHUNG TO RANG SCHIA HET CHO 7
chung minh rang : S= 1/2+1/2^2+1/2^3+.....+1/2^20<1
S=1/2+1/22+1/23+....+1/220<1
2S=1+1/2+1/22+1/23+....+1/2
2S=1+S-1/220
2S-S=1-1/220
S=1-1/220
1-1/220<1
=> S<1
Hơi khó hiểu chút nha bn
Chứng tỏ rằng: 1/3^2+1/4^2+1/5^2+...+1/60^2<4/9
kho vler ai biet thi tra loi gium!