Gía trị của biểu thức: 2/2*5 + 2/5*8 + 2/8*11 + . . . + 2/59*61 là 11/08/2021 Bởi Abigail Gía trị của biểu thức: 2/2*5 + 2/5*8 + 2/8*11 + . . . + 2/59*61 là
Bạn ơi $\frac{2}{59.62}$ nhé. S= $\frac{2}{2.5}$ + $\frac{2}{5.8}$ + $\frac{2}{8.11}$ + … + $\frac{2}{59.62}$ 1,5.S=1,5.($\frac{2}{2.5}$ + $\frac{2}{5.8}$ + $\frac{2}{8.11}$ + … + $\frac{2}{59.62}$) 1,5.S=$\frac{3}{2.5}$ + $\frac{3}{5.8}$ + $\frac{3}{8.11}$ + … + $\frac{3}{59.62}$ 1,5.S=$\frac{1}{2}$ – $\frac{1}{5}$ + $\frac{1}{5}$ – $\frac{1}{8}$ + … + $\frac{1}{59}$ – $\frac{1}{62}$ 1,5.S=$\frac{1}{2}$ – $\frac{1}{62}$ 1,5.S=$\frac{15}{31}$ S=$\frac{10}{31}$ Vậy $\frac{2}{2.5}$ + $\frac{2}{5.8}$ + $\frac{2}{8.11}$ + … + $\frac{2}{59.62}$= $\frac{10}{31}$ Bình luận
Sửa đề: `A = 2/(2. 5) + 2/(5. 8) + … + 2/(59. 62)` `A = 2/(2. 5) + 2/(5. 8) + … + 2/(59. 62)` `⇒ A = 2/3.(1/2 – 1/5 + 1/5 – 1/8 + … + 1/59 – 1/62)` `⇒ A = 2/3.(1/2 – 1/62)` `⇒ A = 2/3. 15/31` `⇒ A = 10/31` Bình luận
Bạn ơi $\frac{2}{59.62}$ nhé.
S= $\frac{2}{2.5}$ + $\frac{2}{5.8}$ + $\frac{2}{8.11}$ + … + $\frac{2}{59.62}$
1,5.S=1,5.($\frac{2}{2.5}$ + $\frac{2}{5.8}$ + $\frac{2}{8.11}$ + … + $\frac{2}{59.62}$)
1,5.S=$\frac{3}{2.5}$ + $\frac{3}{5.8}$ + $\frac{3}{8.11}$ + … + $\frac{3}{59.62}$
1,5.S=$\frac{1}{2}$ – $\frac{1}{5}$ + $\frac{1}{5}$ – $\frac{1}{8}$ + … + $\frac{1}{59}$ – $\frac{1}{62}$
1,5.S=$\frac{1}{2}$ – $\frac{1}{62}$
1,5.S=$\frac{15}{31}$
S=$\frac{10}{31}$
Vậy $\frac{2}{2.5}$ + $\frac{2}{5.8}$ + $\frac{2}{8.11}$ + … + $\frac{2}{59.62}$= $\frac{10}{31}$
Sửa đề: `A = 2/(2. 5) + 2/(5. 8) + … + 2/(59. 62)`
`A = 2/(2. 5) + 2/(5. 8) + … + 2/(59. 62)`
`⇒ A = 2/3.(1/2 – 1/5 + 1/5 – 1/8 + … + 1/59 – 1/62)`
`⇒ A = 2/3.(1/2 – 1/62)`
`⇒ A = 2/3. 15/31`
`⇒ A = 10/31`