1/2+1/4+1/8+1/16+...+1/512=1/1024
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A=\(\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+...+\frac{1}{1024}\)
=\(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{8}+...+\frac{1}{512}-\frac{1}{1024}\)
=1-1/1024
=1023/1024
Đặt S = 1/2 + 1/4 + 1/8 + 1/16 + ...
==> 2S = 1 + 1/2 + 1/4 + 1/8 + 1/16 + ...
2S = 1 + S
==> S = 1
Dãy số đó có số số hạng là :
( 1/1024 - 1 ) :
( 1 + 1/1024 ) *
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Đặt A=1/2+1/4+1/8+..+1/1024
Ax2=1+1/2+1/4+1/8+..+1/512( Nhân cả 2 vế với 2)
Ax2-A=(1+1/2+1/4+1/8+..+1/512)-(1/2+1/4+1/8+..+1/1024)
<=>A=1-1/1024
<=>A=1023/1024
Vậy biểu thức đã cho = 1023/1024
gọi A=1/2+1/4+1/8+...+1/1024
2xA=1+1/2+1/4+.....+1/512
2xA-A=(1+1/2+1/4+....+1/512)-(1/2+1/4+1/8+...+1/1024)
A=1-1/1024
=1023/1024
vậy A=1023/1024
\(\frac{1}{2}+\frac{1}{4}+...+\frac{1}{1024}=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{4}+...+\frac{1}{512}-\frac{1}{1024}=1-\frac{1}{1024}=\frac{1023}{1024}\)
đặt biểu thức là A ta có :
A = 1/2 + 1/4 + 1/8 + 1/16 +1/32 +1/64 +1/128 + 1/256 + 1/512 + 1/102
A x 2 = 1+ 1/2 + 1/4 + 1/8 + 1/16 +1 /32+1/64 + 1/ 128 + 1/256 + 1/512
A = ( 1 + 1/2 +1/4 + 1/ 8+ 1/16 + 1/32 + 1/64 + 1/128 + 1/256 + 1/512 ) - ( 1/2 + 1/4 + 1/8 +1/16 +1/32 + 1/64 + 1/128 +1/256 +1/512 +1/1024)
A = 1 - 1/1024
A = 1023/1024
nhớ k nhé
(1 / 2) + (1 / 4) + (1 / 8) + (1 / 16) + (1 / 32) + (1 / 64) + (1 / 128) + (1 / 256) + (1 / 512) + (1 / 1024) =
0.9990234375
1 + 1 = 2
2 + 2 = 4
4 + 4 = 8
8 + 8 = 16
16 + 16 = 32
32 + 32 = 64
64 + 64 = 128
128 + 128 = 256
256 + 256 = 512
512 + 512 = 1024
1024 + 1024 = 2048
1+1=2
2+2=4
4+4=8
8+8=16
16+16=32
32+32=64
64+64=128
128+128=265
256+256=512
512+512=1024
1024+1024=2048
Học tốt ^_^
-1-1/2-1/4-1/8-1/16-1/32-1/64-1/128-1/256-1/512-1/1024=-1,9990234375
đặt A = 1/2 + 1/4 + 1/8 + 1/16 +...+ 1/512 + 1/1024
2A = 1 + 1/2 + 1/4 + 1/8 +...+ 1/512
2A - A = (1 + 1/2 + 1/4 +...+ 1/512) - (1/2 + 1/4 +...+ 1/512 + 1/1024)
A = 1 + 1/2 + 1/4 +...+ 1/512 - 1/2 - 1/4 -...- 1/512 - 1/1024
A = 1 - 1/1024
A = 1023/1024