A=1+1/2=1/2^2+1/2^3+………….+1/2^2021 bài cô giao 20/08/2021 Bởi Sadie A=1+1/2=1/2^2+1/2^3+………….+1/2^2021 bài cô giao
Tham khảo `A=1+\frac{1}{2}+\frac{1}{2^2}+…+\frac{1}{2^{2021}}` `⇒2A=2+1+\frac{1}{2}+…+\frac{1}{2^{2020}}` `⇒2A-A=2+1+\frac{1}{2}+…+\frac{1}{2^{2020}}-(1+\frac{1}{2}+\frac{1}{2^2}+…+\frac{1}{2^{2021}})` `⇒A=2-\frac{1}{2^{2021}}` `\text{©CBT}` Bình luận
`A=1+1/2=1/2^2+1/2^3+…+1/2^2021` Sửa lại: `A=1+1/2+1/2^2+1/2^3+…+1/2^2021` `=>2A=2+1+1/2+1/2^2+…+1/2^2020` `=>2A-A=(2+1+1/2+1/2^2+…+1/2^2020)-(1+1/2+1/2^2+1/2^3+…+1/2^2021)` `=>A=2-1/2^2013` Vậy `A=2-1/2^2013` Bình luận
Tham khảo
`A=1+\frac{1}{2}+\frac{1}{2^2}+…+\frac{1}{2^{2021}}`
`⇒2A=2+1+\frac{1}{2}+…+\frac{1}{2^{2020}}`
`⇒2A-A=2+1+\frac{1}{2}+…+\frac{1}{2^{2020}}-(1+\frac{1}{2}+\frac{1}{2^2}+…+\frac{1}{2^{2021}})`
`⇒A=2-\frac{1}{2^{2021}}`
`\text{©CBT}`
`A=1+1/2=1/2^2+1/2^3+…+1/2^2021`
Sửa lại: `A=1+1/2+1/2^2+1/2^3+…+1/2^2021`
`=>2A=2+1+1/2+1/2^2+…+1/2^2020`
`=>2A-A=(2+1+1/2+1/2^2+…+1/2^2020)-(1+1/2+1/2^2+1/2^3+…+1/2^2021)`
`=>A=2-1/2^2013`
Vậy `A=2-1/2^2013`