Toán tính tổng B = 2/3.5 + 2/5.7 +… + 2/37.39 22/09/2021 By Caroline tính tổng B = 2/3.5 + 2/5.7 +… + 2/37.39
`B = 2/3.5 + 2/5.7 + … + 2/37.39` `B = 1/3.5 + 1/5.7 + … + 1/37.39` `B = 1/3 – 1/5 + 1/5 – 1/7 + … + 1/37 – 1/39` `B = 1/3 – 1/39` `B = 13/39 – 1/39` `B = 12/39 =4/13` Trả lời
Đáp án: `B=4/13` Giải thích các bước giải: `B = 2/3.5 + 2/5.7 +… + 2/37.39` `B=1/3-1/5+1/5-1/7+…+1/37-1/39` `B=1/3-1/39` `B=13/39-1/39` `B=12/39` `B=4/13`Vậy `B=4/13` Trả lời
`B = 2/3.5 + 2/5.7 + … + 2/37.39`
`B = 1/3.5 + 1/5.7 + … + 1/37.39`
`B = 1/3 – 1/5 + 1/5 – 1/7 + … + 1/37 – 1/39`
`B = 1/3 – 1/39`
`B = 13/39 – 1/39`
`B = 12/39 =4/13`
Đáp án:
`B=4/13`
Giải thích các bước giải:
`B = 2/3.5 + 2/5.7 +… + 2/37.39`
`B=1/3-1/5+1/5-1/7+…+1/37-1/39`
`B=1/3-1/39`
`B=13/39-1/39`
`B=12/39`
`B=4/13`
Vậy `B=4/13`