\(\left(3x-\frac{7}{6}\right):\left(-\frac{19}{2}\right)=\frac{x}{3}\)
<=>
\(\left(3x-\frac{7}{6}\right):\left(-\frac{19}{2}\right)=\frac{x}{3}\)
<=>
tìm số x , biết :
a) \(\frac{2}{3}x-\frac{3}{2}x=\frac{5}{12}\)
b) \(\frac{2}{5}+\frac{3}{5}.\left(3x-3,7\right)=\frac{-53}{10}\)
c) \(\frac{7}{9}:\left(2+\frac{3}{4}x\right)+\frac{5}{9}=\frac{23}{27}\)
d) \(\frac{-2}{3}.x+\frac{1}{5}=\frac{3}{10}\)
e) \(\left|x\right|-\frac{3}{4}=\frac{5}{3}\)
f) \(\left|2x-\frac{1}{3}\right|+\frac{5}{6}=1\)
tìm x , y , z biết
a) \(\frac{x}{2}=\frac{y}{5}\)và 3x - y = 10
b) \(\frac{x}{4}=\frac{y}{5}\)và x.y= 30
c) \(\frac{x}{4}=\frac{y}{4};\frac{y}{3}=\frac{z}{4}\)và 4x + y.z= 16
d) \(\frac{x+1}{2}=\frac{y+2}{3}=\frac{z+2}{4}\)và 3x - 2y + z = 105
Bài 1: Tính các tổng sau một cách hợp lý nhất:
a) \(\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{2016.2017}\) b) \(\frac{2016}{1.3}+\frac{2016}{3.5}+...+\frac{2016}{2015.2017}\)
Bài 2: Tính các tổng sau một cách hợp lý nhất:
a) \(A=\frac{2}{15}+\frac{2}{35}+\frac{2}{63}+\frac{2}{99}+...+\frac{2}{399}\)
b) \(B=\frac{10}{56}+\frac{10}{140}+\frac{10}{260}+...+\frac{10}{1400}\)
c) \(C=\frac{3^2}{8.11}+\frac{3^2}{11.14}+\frac{3^2}{14.17}+...+\frac{3^2}{197.200}\)
Bài 3: Tìm x bt:
a) \(x-\frac{20}{11.13}-\frac{20}{13.15}-\frac{20}{15.17}-...-\frac{20}{53.55}=\frac{3}{11}\)
b) \(\frac{1}{21}+\frac{1}{28}+\frac{1}{36}+...+\frac{2}{x\left(x+1\right)}=\frac{2}{9}\)
Bài 1: tìm x:
a)\(\frac{2}{3}\).x-\(\frac{3}{2}\).x=\(\frac{5}{12}\)
b) \(\frac{7}{9}\):(2+\(\frac{3}{4}\).x)+\(\frac{5}{9}\)=\(\frac{23}{27}\)
c)\(\frac{2}{5}\)+\(\frac{3}{5}\).(3x-3,7)= -\(\frac{53}{10}\)
Bài 14 : Tìm x biết :
a) x: \(4\frac{1}{3}=-2,5\) b) x: \(\frac{-3}{5}=\frac{-10}{21}\) c) \(\frac{2}{3}x-\frac{1}{2}=\frac{1}{10}\) d) \(\frac{1}{2}x+\frac{1}{2}=\frac{5}{2}\)
tìm x:
1) \(\frac{x-4}{12}=\frac{x-6}{11}\)
2)\(\frac{3x+2}{-7}=\frac{x-4}{-2}\)
3)\(\frac{1-4x}{5}=\frac{2x-1}{-3}\)
Tìm số tự nhiên x biết:
\(\frac{1}{3}+\frac{1}{6}+\frac{1}{10}+.....+\frac{2}{x.\left(x+1\right)}=\frac{1999}{2001}\)
\(\frac{1}{10}+\frac{1}{15}+\frac{1}{21}+....+\frac{2}{x.\left(x+1\right)}\)
(x-\(\frac{1}{3}\)).(\(\frac{1}{2}-\frac{2}{5}-\frac{5}{6}\))-\(\frac{1}{2}\)=\(\frac{3}{10}-\frac{1}{4}\)
Tìm x,biết:
a/ \(\frac{x}{3}-\frac{10}{21}=\frac{-1}{7}\)
b/x-25%=\(\frac{1}{2}\)
c/ \(\frac{-5}{6}+\frac{8}{3}+\frac{-29}{6}\le x\le\frac{-1}{2}+2+\frac{5}{2}\)