1\2 + 1\4 + 1\6 + ... + 1\156 + 1\512 = ?
tính: A=1/6-1/39+1/51 / 1/8-1/52+1/68 B=512-512/2-512/2^2-512/2^3-...-512/2^10
?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????/??bố thằng nào mà biết được
1/2+1/4+1/6+1/8+............+1/512
1/2+1/4+1/6+1/8+1/16+...+1/256+1/512 = ?
Đặt A=1/2+1/4+1/6+1/8+1/16+...+1/256+1/512
=(1/2+1/4+1/8+1/16+...+1/256+1/256-1/512)+1/6
=(1-1/2+1/2-1/4+1/4-1/8+1/8-1/16+...+1/128-1/256+1/256-1/512)+1/6
=1-1/512+1/6
=1789/1536
Vậy A=1789/1536
Tính
A= 512 - 512/2 - 512/2^2 - 512/2^3 - ....- 512/210
E= 1 - 1/10 - 1/15 - 1/3 - 1/28 - 1/6 - 1/21
C= 11/1.3 + 47/3.5 + 107/5.7 + 191/7.9 +...+ 971/17.19
sai bet thang ngu nhu cho
tính A=1/6-1/39+1/51 / 1/8-1/52+1/68 ; B= 512-512/2-512/2^2-212/2^3-...-512/2^10
a)1/2+1/6+1/12+........+1/9900+1/10100
b)1/2+1/4+1/8+....+1/256+1/512
a, \(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+....+\frac{1}{10100}\)
=\(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+....+\frac{1}{100.101}\)
=\(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+......+\frac{1}{100}-\frac{1}{101}\)
=\(1-\frac{1}{101}\)
=\(\frac{100}{101}\)
b,\(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+....+\frac{1}{512}\)
=\(\left(1-\frac{1}{2}\right)+\left(\frac{1}{2}-\frac{1}{4}\right)+\left(\frac{1}{4}-\frac{1}{8}\right)+...+\left(\frac{1}{256}-\frac{1}{512}\right)\)
=\(1-\frac{1}{512}\)
=\(\frac{511}{512}\)
\(\frac{1}{2}+\frac{1}{6}+...+\frac{1}{9900}+\frac{1}{10100}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{99}-\frac{1}{100}+\frac{1}{100}-\frac{1}{101}\)
\(=1-\frac{1}{101}=\frac{100}{101}\)
a)1/2+1/6+1/12+.........+1/9900+1/10100 = ?
b)1/2+1/4+1/8+...........+1/256+1/512 = ?
a) trieu dang làm rồi
b) A= 1/2 + 1/4+ 1/8+ 1/16 + 1/32 + 1/64 + 1/128 + 1/256 + 1/512
A = 1 - 1/2 + 1/2- 1/4 + 1/4 - 1/8 + 1/8 - 1/16 + 1/16 - 1/32 + 1/32 - 1/64 + 1/64 - 1/128 + 1/128 - 1/256 - 1/256 - 1/512
A = 1 - 1/512
A = 511/512
A=1+4+7+....+100
B=1+2+4+6+.....+100
C=1+2+4+8+....+512
a) Số số hạng : (100-1):3+1=34
Tổng : (100+1).34:2=1717
b) 1+2+4+6+...+100=1+(2+4+6+...+100)
Xét tổng 2+4+6+..+100 có:
Số số hạng : (100-2):2+1=50
Tổng : (100+2).50:2=2550
-) Số số hạng của A là : ( 100 - 1 ) : 3 + 1 = 34 ( số hạng )
A = 1 + 4 + 7 + .... + 100
= ( 100 + 1 ) x 34 : 2
= 101 x 34 : 2
= 1717
-) Gọi D = 2 + 4 + 6 + .... + 100
Số số hạng của D là : ( 100 - 2 ) : 2 + 1 = 50 ( số hạng )
D = ( 100 + 2 ) x 50 : 2
= 102 x 50 : 2
= 2550
=> B = 1 + 2 + 4 + 6 + ..... + 100
= 1 + 2550
= 2551
-)
C = 1 + 2 + 4 + 8 + .... + 512
= 20 + 21 + 22 + 23 + .... + 29
=> 2C = 21 + 22 + 23 + .... + 29 + 210
=> 2C - C = ( 21 + 22 + 23 + .... + 29 + 210) - ( 20 + 21 + 22 + 23 + .... + 29 )
C = 210 - 2
> Chúc bạn học tốt <
A=1+4+7+....+100
B=1+2+4+6+.....+100
C=1+2+4+8+....+512
A=[(100-1):3+1].(100+1):2
A=34.101:2=1717
A=1+4+7+...+100
SSH: (100-1):3+1=34
Tổng: (100+1).34:2=1717
Bài B và C hình như đề bài sai hay sao ấy!!!