Toán A=1/2 + 1/4 + 1/8 + ….+ 1/512 + 1/1024 30/06/2021 By Sarah A=1/2 + 1/4 + 1/8 + ….+ 1/512 + 1/1024
`A=1/2+1/4+1/8+…+1/512+1/1024` `⇒2A=1+1/2+1/4+…+1/256+1/512` `⇒2A-A=(1+1/2+1/4+…+1/256+1/512)-(1/2+1/4+1/8+…+1/512+1/1024)` `⇒A=1-1/1024` `⇒A=1023/1024` Trả lời
A=1/2 + 1/4 + 1/8 + … + 1/512 + 1/1024A x 2=1 – (1/2 + 1/4 + 1/8 + … + 1/512 + 1/1024) – 1/1024A x 2=1 – 1/1024 + AA x 2 – A=1 – 1/1024A=1023/1024 Trả lời
`A=1/2+1/4+1/8+…+1/512+1/1024`
`⇒2A=1+1/2+1/4+…+1/256+1/512`
`⇒2A-A=(1+1/2+1/4+…+1/256+1/512)-(1/2+1/4+1/8+…+1/512+1/1024)`
`⇒A=1-1/1024`
`⇒A=1023/1024`
A=1/2 + 1/4 + 1/8 + … + 1/512 + 1/1024
A x 2=1 – (1/2 + 1/4 + 1/8 + … + 1/512 + 1/1024) – 1/1024
A x 2=1 – 1/1024 + A
A x 2 – A=1 – 1/1024
A=1023/1024