Tính tổng : S= 1/2×3 + 1/3×4 + ……..+ 1/9×10 23/09/2021 Bởi Mackenzie Tính tổng : S= 1/2×3 + 1/3×4 + ……..+ 1/9×10
`1/(2.3) + 1/(3.4) + ….. + 1/(9.10)` `= 1/2-1/3+ 1/3-1/4 + ….. + 1/9 – 1/10` `= 1/2 – 1/10` `= 5/10 – 1/10` `= 4/10 = 0,4` (Chúc bạn học tốt). Bình luận
S = $\dfrac{1}{2.3}$ + $\dfrac{1}{3.4}$ +…+$\dfrac{1}{9.10}$ => S = $\dfrac{1}{2}$ – $\dfrac{1}{3}$ + $\dfrac{1}{3}$ – $\dfrac{1}{4}$ + …..+ $\dfrac{1}{9}$ – $\dfrac{1}{10}$ => S = $\dfrac{1}{2}$ – $\dfrac{1}{10}$ => S = $\dfrac{5}{10}$ – $\dfrac{1}{10}$ => S = $\dfrac{4}{10}$ = $\dfrac{2}{5}$ Bình luận
`1/(2.3) + 1/(3.4) + ….. + 1/(9.10)`
`= 1/2-1/3+ 1/3-1/4 + ….. + 1/9 – 1/10`
`= 1/2 – 1/10`
`= 5/10 – 1/10`
`= 4/10 = 0,4`
(Chúc bạn học tốt).
S = $\dfrac{1}{2.3}$ + $\dfrac{1}{3.4}$ +…+$\dfrac{1}{9.10}$
=> S = $\dfrac{1}{2}$ – $\dfrac{1}{3}$ + $\dfrac{1}{3}$ – $\dfrac{1}{4}$ + …..+ $\dfrac{1}{9}$ – $\dfrac{1}{10}$
=> S = $\dfrac{1}{2}$ – $\dfrac{1}{10}$
=> S = $\dfrac{5}{10}$ – $\dfrac{1}{10}$
=> S = $\dfrac{4}{10}$ = $\dfrac{2}{5}$