tìm x biết 5/1×6+5/6×11+ … +5/(5x+1)(5x+6)=2019/2020 09/10/2021 Bởi aikhanh tìm x biết 5/1×6+5/6×11+ … +5/(5x+1)(5x+6)=2019/2020
5/1.6+5/6.11+…+5/(5x+1)(5x+6)=2019/2020 ⇔1-1/6+1/6-1/11+…+1/5x-1-1/5x+6=2019/2020 ⇔1-1/5x+6=2019/2020 ⇔1/5x+6=1-2019/2020 ⇔1/5x+6=1/2020 ⇔5x+6=1:1/2020 ⇔5x+6=2020 ⇔5x=2020-6 ⇔5x=2014 ⇔x=2014:5 ⇔x=2014/5 ⇔x=402,8. Vậy x=402,8. Bình luận
$\dfrac{5}{1.6} + \dfrac{5}{6.11} + ….. + \dfrac{5}{(5x+1)(5x+6)}= \dfrac{2019}{2020}$ $⇔ 1 – \dfrac{1}{5x+6} = \dfrac{2019}{2020}$ $⇔ \dfrac{1}{5x+6} = \dfrac{1}{2020}$ $⇔ 5x + 6 = 2020$ $⇔ 5x = 2014$ $⇔ x = \dfrac{2014}{5}$ Vậy $x= \dfrac{2014}{5}$ Bình luận
5/1.6+5/6.11+…+5/(5x+1)(5x+6)=2019/2020
⇔1-1/6+1/6-1/11+…+1/5x-1-1/5x+6=2019/2020
⇔1-1/5x+6=2019/2020
⇔1/5x+6=1-2019/2020
⇔1/5x+6=1/2020
⇔5x+6=1:1/2020
⇔5x+6=2020
⇔5x=2020-6
⇔5x=2014
⇔x=2014:5
⇔x=2014/5
⇔x=402,8.
Vậy x=402,8.
$\dfrac{5}{1.6} + \dfrac{5}{6.11} + ….. + \dfrac{5}{(5x+1)(5x+6)}= \dfrac{2019}{2020}$
$⇔ 1 – \dfrac{1}{5x+6} = \dfrac{2019}{2020}$
$⇔ \dfrac{1}{5x+6} = \dfrac{1}{2020}$
$⇔ 5x + 6 = 2020$
$⇔ 5x = 2014$
$⇔ x = \dfrac{2014}{5}$
Vậy $x= \dfrac{2014}{5}$