Đáp án:
~~ Bạn tham khảo
Đặt `M=1 - 1/2 - 1/4 - 1/8 - 1/16 - 1/32 - .......... - 1/1024 - 1/2048`
`2M= 2 . (1 - 1/2 - 1/4 - 1/8 - 1/16 - 1/32 - .......... - 1/1024 - 1/2048)`
`2M = 2 - 1 - 1/2 - 1/4 - 1/8 - 1/16 - ............. - 1/512 - 1/1024`
`2M - M = (2 - 1 - 1/2 - 1/4 - 1/8 - 1/16 - ............. - 1/512 - 1/1024) - ( 1 - 1/2 - 1/4 - 1/8 - 1/16 - 1/32 - .......... - 1/1024 - 1/2048)`
`2M - M = 2 - 1 - 1/2 - 1/4 - 1/8 - 1/16 - ............. - 1/512 - 1/1024 - 1 + 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + .......... + 1/1024 + 1/2048`
`2M - M = 2 - 1 - 1 -( 1/2-1/2) - (1/4-1/4)-(1/8-1/8)-................. - (1/1024 - 1/1024) + 1/2048`
`M = 1/2048`
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