(31-1)(-1/2x+5)=0
x-20/11-20/13.15-20/15.17-...........-22/53.55=3/11
tìm x nhé các bn
bn nào giúp mk sẽ tick cho 3 tick
yêu các bn nhìu
(31-1)(-1/2x+5)=0
x-20/11-20/13.15-20/15.17-...........-22/53.55=3/11
tìm x nhé các bn
bn nào giúp mk sẽ tick cho 3 tick
yêu các bn nhìu
a) \(\left(31-1\right)\left(\dfrac{-1}{2}x+5\right)=0\)
\(30\left(\dfrac{-1}{2}x+5\right)=0\)
\(\left(\dfrac{-1}{2}x+5\right)=0:30\)
\(\dfrac{-1}{2}x+5=0\)
\(\dfrac{-1}{2}x=0-5\)
\(\dfrac{-1}{2}x=-5\)
\(x=-5:\dfrac{-1}{2}\)
\(x=10\)
b) \(x-\dfrac{20}{11.13}-\dfrac{20}{13.15}-\dfrac{20}{15.17}-...-\dfrac{20}{53.55}=\dfrac{3}{11}\)
\(x-10\left(\dfrac{2}{11.13}+\dfrac{2}{13.15}+\dfrac{2}{15.17}+...+\dfrac{2}{53.55}\right)=\dfrac{3}{11}\)
\(x-10\left(\dfrac{1}{11}-\dfrac{1}{13}+\dfrac{1}{13}-\dfrac{1}{15}+\dfrac{1}{15}-\dfrac{1}{17}+...+\dfrac{1}{53}-\dfrac{1}{55}\right)=\dfrac{3}{11}\) \(x-10\left(\dfrac{1}{11}-\dfrac{1}{55}\right)=\dfrac{3}{11}\) \(x-10.\dfrac{4}{55}=\dfrac{3}{11}\) \(x-\dfrac{8}{11}=\dfrac{3}{11}\) \(x=\dfrac{3}{11}+\dfrac{8}{11}=1\)a) (31/20 - 26/45) . -36<x<(51/56+8/21+1/3)-8/13.
b)(2/11.13 + 2/13.15 + 2/15.17+...+2/53.55)- x + 22/2 - 1/31=4/3.
c)(x+5).(3x-12)>0
giúp mình vs nhé tick
tìm x là số tự nhiên , biết a, x-20/11.13-20/13.15-20/15.17-...-20/53.55=3/11
b, 1/21+1/28+1/36+...+2/x(x+1)=2/9
Làm ơn giúp mình , ai giúp mình mình tick cho
1.Tìm X thuộc N
a. x-20/11.13-20/13.15-20/15.17-...-20/53.55=3/11
b. 1/21+1/28+1/36+...+2/x.(x+1)=2/9
Tim x
A,x - ( 20 / 11.13+20/13.15+20/15.17+...+20/53.55)=3/11
B,1/21+1/28+1/36+...+2/x.(x+1)=2/9
a) \(x-\left(\frac{20}{11.13}+\frac{20}{13.15}+\frac{20}{15.17}+...+\frac{20}{53.55}\right)=\frac{3}{11}\)
\(x-\frac{20}{2}.\left(\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}+\frac{1}{15}-\frac{1}{17}+...+\frac{1}{53}-\frac{1}{55}\right)=\frac{3}{11}\)
\(x-10.\left(\frac{1}{11}-\frac{1}{55}\right)=\frac{3}{11}\)
\(x-10.\frac{4}{55}=\frac{3}{11}\)
\(x-\frac{8}{11}=\frac{3}{11}\)
x = 1
b) \(\frac{1}{21}+\frac{1}{28}+\frac{1}{36}+...+\frac{2}{x.\left(x+1\right)}=\frac{2}{9}\)
\(\Rightarrow\frac{2}{42}+\frac{2}{56}+\frac{2}{72}+...+\frac{2}{x.\left(x+1\right)}=\frac{2}{9}\) ( nhân cho cả tử và mẫu của các số hạng trên ( ngoại trừ 2/x.(x+1) ) là 2)
\(\frac{2}{6.7}+\frac{2}{7.8}+\frac{2}{8.9}+...+\frac{2}{x.\left(x+1\right)}=\frac{2}{9}\)
\(2.\left(\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}+\frac{1}{8}-\frac{1}{9}+...+\frac{1}{x}-\frac{1}{x+1}\right)=\frac{2}{9}\)
\(2.\left(\frac{1}{6}-\frac{1}{x+1}\right)=\frac{2}{9}\)
\(\frac{1}{6}-\frac{1}{x+1}=\frac{1}{9}\)
\(\frac{1}{x+1}=\frac{1}{18}\)
=> x + 1 = 18
x = 17
\(a,x-\left(\frac{20}{11.13}+\frac{20}{13.15}+...+\frac{20}{53.55}\right)=\frac{3}{11}\)
\(\Rightarrow x-10\left(\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}+...+\frac{1}{53}-\frac{1}{55}\right)=\frac{3}{11}\)
\(\Rightarrow x-10\left(\frac{1}{11}-\frac{1}{55}\right)=\frac{3}{11}\)
\(\Rightarrow x-\frac{8}{11}=\frac{3}{11}\)
\(\Rightarrow x=1\)
\(b,\frac{1}{21}+\frac{1}{28}+\frac{1}{36}+...+\frac{2}{x\left(x+1\right)}=\frac{2}{9}\)
\(\frac{2}{42}+\frac{2}{56}+...+\frac{2}{x\left(x+1\right)}=\frac{2}{9}\)
\(2\left(\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}+...+\frac{1}{x}-\frac{1}{x+1}\right)=\frac{2}{9}\)
\(\Rightarrow\frac{1}{6}-\frac{1}{x+1}=\frac{1}{9}\)
\(\Rightarrow\frac{1}{18}=\frac{1}{x+1}\)
\(\Rightarrow x+1=18\Leftrightarrow x=17\)
Bài 1: Tính:
A= 1001. (5/111111+ 5/222222- 4/3.7.11.13.17)
Bài 2: Tìm x:
a) x- 20/11.13- 20/13.15- 20/15.17-................-20/53.55= 3/11
b) (x+ 1/4- 1/3) : (2+ 1/6- 1/4)= 7/46
c) 13/15- (13/21+ x). 7/12= 7/10
a) x - 20/11.13 - 20/13.15 - 20/15.17 -...- 20/53.55 = 3/11
b) 1/21 + 1/28 + 1/36+...+ 2/x(x+1) = 2/9
Giúp với. Khó quá!! cơ hội kiếm like :))
\(x-\frac{20}{11.13}-\frac{20}{23.15}-....-\frac{20}{53.55}=\frac{3}{11}\)
\(x-\left(\frac{20}{11.13}+\frac{20}{13.15}+....+\frac{20}{53.55}\right)=\frac{3}{11}\)
\(x-10\left(\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}+...+\frac{1}{53}-\frac{1}{55}\right)=\frac{3}{11}\)
\(x-10\left(\frac{1}{11}-\frac{1}{55}\right)=\frac{3}{11}\)
\(x-\frac{8}{11}=\frac{3}{11}\)
=> \(x=\frac{3}{11}+\frac{8}{11}=1\)
Tìm x biết:
a) \(\dfrac{x+5}{3}\)=\(\dfrac{x-6}{7}\)
b) x - \(\dfrac{20}{11.13}\)-\(\dfrac{20}{13.15}\)-\(\dfrac{20}{15.17}\)-...-\(\dfrac{20}{53.55}\)=\(\dfrac{3}{11}\)
\(\dfrac{1}{3}\)+\(\dfrac{1}{6}\)+\(\dfrac{1}{10}\)+...+\(\dfrac{2}{n\left(n+1\right)}\)=\(\dfrac{2015}{2016}\)
a) Vì \(\dfrac{x+5}{3}\)= \(\dfrac{x-6}{7}\) nên 7(x+5) = 3(x-6)
=> 7x+ 35 = 3x - 18
7x - 3x = -18 -35
4x = -53
x = -53:4
x = \(\dfrac{-53}{4}\)
