A=1/2+1/4+1/8.....+1/256+1/512

2A=1+1/2+1/4+1/8...1/256

A=(1+1/2+1/4+1/8...1/256)-(1/2+1/4+1/8.....+1/256+1/512)

A=1-1/512

A=511/512

511/512

Các số là : 

(512 + 1 ) :  1 + 1 = 512 (so )

Tổng trên là : 

(512 - 1 ) .512 : 2= 130816

​Vậy tổng trên bằng 130816

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

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=256

256+256=512

512+512=1024

1+1=2

2+2=4

4+4=8

8+8=16

16+16=32

32+32=64

64+64=128

128+128=156

256+256=512

512+512=1024

Lần lượt nhe:2

                    4

                    8

                    16

                    32

                    128

                    256

                    512

                    1024

các tổng này đều = các số hạng của phép tính trên đúng ko

\(A=\dfrac{1}{2}+\dfrac{1}{2^2}+\dfrac{1}{2^3}+...+\dfrac{1}{2^9}\\ 2A=1+\dfrac{1}{2}+\dfrac{1}{2^2}+...+\dfrac{1}{2^8}\\ 2A-A=\left(1+\dfrac{1}{2}+...+\dfrac{1}{2^8}\right)-\left(\dfrac{1}{2}+\dfrac{1}{2^2}+...+\dfrac{1}{2^9}\right)\\ A=1-\dfrac{1}{2^9}=\dfrac{511}{512}\)

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 

2048 + 2048 = 4096

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

2048+2048=4096

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

2048+2048=4096

\(D=\dfrac{1}{2}+\dfrac{1}{4}+\dfrac{1}{8}+..........+\dfrac{1}{256}+\dfrac{1}{512}\)

\(\Leftrightarrow2D=1+\dfrac{1}{2}+\dfrac{1}{4}+......+\dfrac{1}{256}\)

\(\Leftrightarrow2D-D=\left(1+\dfrac{1}{2}+.....+\dfrac{1}{256}\right)-\left(\dfrac{1}{2}+\dfrac{1}{4}+.....+\dfrac{1}{512}\right)\)

\(\Leftrightarrow D=1-\dfrac{1}{512}=\dfrac{511}{512}\)

= 511/512

\(A=\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+...+\frac{1}{256}+\frac{1}{512}\)

\(A\cdot2=1+\frac{1}{2}+\frac{1}{4}+\frac{1}{8}+...+\frac{1}{256}\)

\(A\cdot2-A=1-\frac{1}{512}\)

\(A=\frac{511}{512}\)

1/2+1/4+1/8+1/16+...+1/256+1/512(gọi A là tổng các PS trên)

A*2=(1+1/2+1/4+1/8+...+1/128+1/256)/2

A*2-A=1+1/2+1/4+1/8+...+1/128+1/256-1/2-1/4-1/8-1/16-...-1/256-1/512.

A=1-1/512

A=511/512.

Kết bạn với mình nha!