K
Khách
Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
Các câu hỏi dưới đây có thể giống với câu hỏi trên
23 tháng 8 2019
\(A=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}\)
= \(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}\)
= \(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}\)
= \(1-\frac{1}{7}\)
= \(\frac{7}{7}-\frac{1}{7}\)
= \(\frac{6}{7}\)
2) \(\frac{7}{4}-x.\frac{4}{3}=\frac{5}{19}\)
\(x.\frac{4}{3}=\frac{7}{4}-\frac{5}{19}\)
\(x.\frac{4}{3}=\frac{133}{76}-\frac{20}{76}\)
\(x.\frac{4}{3}=\frac{113}{76}\)
\(x=\frac{113}{76}:\frac{4}{3}\)
\(x=\frac{399}{304}\)
VẬY \(x=\frac{399}{304}\)
b) \(\left(x+\frac{3}{4}\right).\frac{5}{7}=\frac{10}{9}\)
\(\left(x+\frac{3}{4}\right)=\frac{10}{9}:\frac{5}{7}\)
\(x+\frac{3}{4}=\frac{14}{9}\)
\(x=\frac{14}{9}-\frac{3}{4}\)
\(x=\frac{29}{36}\)
Vậy \(x=\frac{29}{36}\)
c) \(x.\frac{1}{2}+\frac{3}{2}.x=\frac{4}{5}\)
\(x.\left(\frac{1}{2}+\frac{3}{2}\right)=\frac{4}{5}\)
\(x.2=\frac{4}{5}\)
\(x=\frac{4}{5}:2\)
\(x=\frac{2}{5}\)
Vậy \(x=\frac{2}{5}\)
Chúc bạn học tốt !!!
LL
1
23 tháng 6 2021
2/3:x=7/10 X x5/9=5/18
x=7/10:2/3 x=5/18:5/9
x=21/20 x=1/2
NT
2
17 tháng 9 2017
x*3/5+x*2/7=31/70
x*(3/5+2/7) =31/70
x*31/35 =31/70
x =31/70 :31/35
x = 1/2
17 tháng 9 2017
\(x.\frac{3}{5}+x.\frac{2}{7}=\frac{31}{70}\)
\(x\left(\frac{3}{5}+\frac{2}{7}\right)=\frac{31}{70}\)
\(x\left(\frac{21}{35}+\frac{10}{35}\right)=\frac{31}{70}\)
\(\frac{31}{35}x=\frac{31}{70}\)
\(x=\frac{31}{70}:\frac{31}{35}\)
\(x=\frac{31}{70}.\frac{35}{31}\)
\(x=\frac{35}{70}\)
\(x=\frac{1}{2}\)
vay \(x=\frac{1}{2}\)
C
18 tháng 5 2022
`a)4/5:3/x xx2/11=24/165`
`(4/5xx2/11)xx 3/x=8/55`
`8/55xx3/x=8/55`
`3/x=8/55:8/55`
`3/x=1`
`3:x=1`
`x=3:1`
`x=3`
____________________________________________
`b)4/3:x/5=5/13xx4/9`
`4/3:x/5=20/117`
`x/5=4/3:20/117`
`x/5=39/5`
`x=39`
C
18 tháng 5 2022
A) 4/5:3/x X 2/11=24/165
\(\dfrac{4}{5}:\dfrac{3}{x}X\dfrac{2}{11}=\dfrac{24}{165}\)
\(\dfrac{3}{x}=\dfrac{24}{165}:\dfrac{4}{5}:\dfrac{2}{11}\)
\(\dfrac{3}{x}=1\)
\(\dfrac{3}{x}=\dfrac{3}{3}\)
=> x=3
B) \(\dfrac{4}{3}:\dfrac{x}{5}=\dfrac{5}{13}x\dfrac{4}{9}\)
\(\dfrac{4}{3}:\dfrac{x}{5}=\dfrac{20}{117}\)
\(\dfrac{x}{5}=\dfrac{4}{3}:\dfrac{20}{117}\)
\(\dfrac{x}{5}=\dfrac{39}{5}\)
=> x = 39
3/7 x x = 1/3
x = 1/3 : 3/7
x = 7/9
3/5 : x = 2/3
x = 2/3 x 3/5
x = 6/15 = 2/5
3/7 * x = 1/3
x = 1/3 : 3/ 7 = 7/9
3/5 : x = 2/3
x = 3/5 : 2/3 = 9/10