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15 tháng 5 2022
a: (x+1/2)(2/3-2x)=0
=>x+1/2=0 hoặc 2/3-2x=0
=>x=-1/2 hoặc x=1/3
b: 
c: \(\Leftrightarrow x\cdot\left(\dfrac{13}{4}-\dfrac{7}{6}\right)=\dfrac{5}{12}+\dfrac{5}{3}=\dfrac{5}{12}+\dfrac{20}{12}=\dfrac{25}{12}\)
\(\Leftrightarrow x=\dfrac{25}{12}:\dfrac{39-14}{12}=\dfrac{25}{25}=1\)
TT
8 tháng 9 2017
a.\(\dfrac{5}{3}x-2\dfrac{1}{3}=-\dfrac{4}{3}.1\dfrac{1}{8}-\dfrac{2}{3}\)
\(\dfrac{5}{3}x-2\dfrac{1}{3}=\dfrac{5}{6}\)
\(\dfrac{5}{3}x=\dfrac{5}{6}+2\dfrac{1}{3}\)
\(\dfrac{5}{3}x=\dfrac{19}{6}\)
\(x=\dfrac{19}{5}:\dfrac{5}{3}\)
\(x=\dfrac{19}{10}\)
b. \(2\dfrac{1}{6}:x-\dfrac{-5}{8}=\dfrac{-7}{15}:4\dfrac{1}{5}-\dfrac{-6}{7}\)
\(2\dfrac{1}{6}:x+\dfrac{5}{8}=\dfrac{47}{63}\)
\(2\dfrac{1}{6}:x=\dfrac{47}{63}-\dfrac{5}{8}\)
\(2\dfrac{1}{6}:x=\dfrac{61}{504}\)
\(x=2\dfrac{1}{6}:\dfrac{61}{504}\)
\(x=\dfrac{1092}{61}\)
DH
8 tháng 9 2017
a, \(\dfrac{5}{3}x-2\dfrac{1}{3}=-\dfrac{4}{3}.1\dfrac{1}{8}-\dfrac{2}{3}\)
\(\Rightarrow\dfrac{5}{3}x=-\dfrac{3}{2}-\dfrac{2}{3}+2\dfrac{1}{3}=-\dfrac{3}{2}+2=\dfrac{1}{2}\)
\(\Rightarrow x=\dfrac{1}{2}:\dfrac{5}{3}=\dfrac{3}{10}\)
b, \(2\dfrac{1}{6}:x-\dfrac{-5}{8}=\dfrac{-7}{15}:4\dfrac{1}{5}-\dfrac{-6}{7}\)
\(\Rightarrow\dfrac{13}{6}:x=-\dfrac{7}{15}:\dfrac{21}{5}+\dfrac{6}{7}-\dfrac{5}{8}\)
\(\Rightarrow\dfrac{13}{6}:x=\dfrac{61}{504}\Rightarrow x=\dfrac{1092}{61}\)
c, \(\left(\dfrac{5}{6}x-0,3\right):2\dfrac{1}{3}=25\%\)
\(\Rightarrow\dfrac{5}{6}x-0,3=\dfrac{1}{4}.\dfrac{7}{3}\)
\(\Rightarrow\dfrac{5}{6}x=\dfrac{7}{12}+0,3=\dfrac{53}{60}\)
\(\Rightarrow x=\dfrac{53}{60}:\dfrac{5}{6}=1,06\)
d, \(\dfrac{4}{7}-\dfrac{2}{3}x=1,5+\dfrac{4}{5}x\)
\(\Rightarrow\dfrac{4}{5}x+\dfrac{2}{3}x=\dfrac{4}{7}-1,5\)
\(\Rightarrow\dfrac{22}{15}x=-\dfrac{13}{14}\Rightarrow x=-\dfrac{195}{308}\)
Chúc bạn học tốt!!!
24 tháng 5 2022
a: \(=\dfrac{-3}{7}+\dfrac{-9}{35}-\dfrac{2}{5}\)
\(=\dfrac{-15-9-14}{35}=\dfrac{-38}{35}\)
b: \(=\left(\dfrac{15}{24}-\dfrac{7}{12}\right)\cdot\dfrac{-12}{7}\)
\(=\dfrac{15-14}{24}\cdot\dfrac{-12}{7}=\dfrac{1}{24}\cdot\dfrac{-12}{7}=\dfrac{-1}{14}\)
c: \(=\dfrac{7}{5}\cdot\dfrac{15}{19}\cdot\dfrac{-8}{15}+\dfrac{7}{15}\)
\(=\dfrac{-56}{95}+\dfrac{7}{15}\)
\(=\dfrac{-7}{57}\)
Q
2 tháng 4 2017
1. Tìm \(x\):
a) \(\dfrac{x}{5}=\dfrac{5}{6}+\dfrac{-19}{30}\)
\(\dfrac{x}{5}=\dfrac{1}{5}\)
\(\Rightarrow x=1\)
b) \(\dfrac{-5}{6}-x=\dfrac{7}{12}-\dfrac{1}{3}.x\)
\(\dfrac{-5}{6}-\dfrac{7}{12}=x-\dfrac{1}{3}.x\)
\(x-\dfrac{1}{3}.x=\dfrac{-17}{12}\)
\(\dfrac{2}{3}.x=\dfrac{-17}{12}\)
\(x=\dfrac{-17}{12}:\dfrac{2}{3}\)
\(x=\dfrac{-17}{8}\)
c) \(2016^3.2016^x=2016^8\)
\(2016^x=2016^8:2016^3\)
\(2016^x=2016^{8-3}\)
\(2016^x=2016^5\)
\(\Rightarrow x=5\)
d) \(\left(x+\dfrac{3}{4}\right):\dfrac{5}{2}=3\dfrac{1}{2}\)
\(\left(x+\dfrac{3}{4}\right):\dfrac{5}{2}=\dfrac{7}{2}\)
\(\left(x+\dfrac{3}{4}\right)=\dfrac{7}{2}.\dfrac{5}{2}\)
\(x+\dfrac{3}{4}=\dfrac{35}{4}\)
\(x=\dfrac{35}{4}-\dfrac{3}{4}\)
\(x=\dfrac{32}{4}=8\)
e) \(\left(2,8.x-2^5\right):\dfrac{2}{3}=3^2\)
\(\left(2,8.x-2^5\right)=9.\dfrac{2}{3}\)
\(2,8.x-2^5=6\)
\(2,8.x=6+32\)
\(2,8.x=38\)
\(x=38:2,8\)
\(x=\dfrac{95}{7}\)
f) \(\dfrac{4}{7}.x-\dfrac{2}{3}=\dfrac{2}{5}\)
\(\dfrac{4}{7}.x=\dfrac{2}{5}+\dfrac{2}{3}\)
\(\dfrac{4}{7}.x=\dfrac{16}{15}\)
\(x=\dfrac{16}{15}:\dfrac{4}{7}\)
\(x=\dfrac{28}{15}\)
g) \(\left(\dfrac{3x}{7}+1\right):\left(-4\right)=\dfrac{-1}{28}\)
\(\left(\dfrac{3x}{7}+1\right)=\dfrac{-1}{28}.\left(-4\right)\)
\(\dfrac{3x}{7}+1=\dfrac{1}{7}\)
\(\dfrac{3x}{7}=\dfrac{1}{7}-1\)
\(\dfrac{3x}{7}=\dfrac{-6}{7}\)
\(\Rightarrow3x=-6\)
\(x=\left(-6\right):3\)
\(x=-2\)
Q
2 tháng 4 2017
2. Thực hiện phép tính:
a) \(\dfrac{1}{2}+\dfrac{1}{2}.\dfrac{2}{3}-\dfrac{1}{3}:\dfrac{3}{4}+1\dfrac{4}{5}\)
\(=\dfrac{1}{2}.\left(\dfrac{2}{3}+1\right)-\dfrac{1}{3}:\dfrac{3}{4}+\dfrac{9}{5}\)
\(=\dfrac{1}{2}.\dfrac{5}{3}-\dfrac{1}{3}:\dfrac{3}{4}+\dfrac{9}{5}\)
\(=\dfrac{5}{6}-\dfrac{4}{9}+\dfrac{9}{5}\)
\(=\dfrac{7}{18}+\dfrac{9}{5}\)
\(=\dfrac{197}{90}\)
b) \(\dfrac{7.5^2-7^2}{7.24+21}\)
\(=\dfrac{7.25-7.7}{7.24+7.3}\)
\(=\dfrac{7.\left(25-7\right)}{7.\left(24+3\right)}\)
\(=\dfrac{7.18}{7.27}\)
\(=\dfrac{2}{3}\)
c) \(\dfrac{2}{3}+\dfrac{1}{3}.\left(\dfrac{-4}{9}+\dfrac{5}{6}\right):\dfrac{7}{12}\)
\(=\dfrac{2}{3}+\dfrac{1}{3}.\dfrac{7}{18}:\dfrac{7}{12}\)
\(=\dfrac{2}{3}+\dfrac{7}{54}:\dfrac{7}{12}\)
\(=\dfrac{2}{3}+\dfrac{2}{9}\)
\(=\dfrac{8}{9}\)
21 tháng 5 2022
a: Sửa đề: \(\left[\left(6\dfrac{3}{7}-\dfrac{0,75x-2}{0,35}\right)\cdot2.8+1.75\right]\cdot0.05=2.35\)
\(\Leftrightarrow\left(\dfrac{45}{7}-\dfrac{15x-40}{7}\right)\cdot2.8+1,75=47\)
\(\Leftrightarrow\dfrac{45-15x+40}{7}\cdot2,8=45,25\)
\(\Leftrightarrow\dfrac{85-15x}{7}=\dfrac{905}{56}\)
=>8(85-15x)=905
=>680-120x=905
=>120x=-225
hay x=-15/8
b: \(\dfrac{3}{5}-\dfrac{2}{7}< \dfrac{2}{3}x+\dfrac{3}{4}< \dfrac{1}{2}+\dfrac{7}{9}\)
\(\Leftrightarrow\dfrac{11}{35}-\dfrac{3}{4}< \dfrac{2}{3}x< \dfrac{23}{18}-\dfrac{3}{4}\)
\(\Leftrightarrow-\dfrac{61}{140}< \dfrac{2}{3}x< \dfrac{19}{36}\)
\(\Leftrightarrow-\dfrac{183}{280}< x< \dfrac{19}{24}\)
15 tháng 4 2018
c)
\(\left|\dfrac{2}{3}x-\dfrac{1}{2}\right|-1=\dfrac{5}{6}\)
\(\Leftrightarrow\left|\dfrac{4x-3}{6}\right|=1+\dfrac{5}{6}=\dfrac{11}{6}\)
\(\Leftrightarrow\left|4x-3\right|=11\Leftrightarrow\left[{}\begin{matrix}4x-3=11=>x=\dfrac{11+3}{4}=\dfrac{7}{2}\\4x-3=-11=>x=\dfrac{-8}{2}=-4\end{matrix}\right.\)
13 tháng 7 2018
ta có
\(2.\left(\dfrac{1}{3}+\dfrac{1}{13}+\dfrac{1}{11}+\dfrac{1}{6}\right)\) \(5.\left(\dfrac{1}{4}+\dfrac{1}{7}+\dfrac{1}{6}+\dfrac{1}{11}\right)\)
_______________________ X ________________________
\(4.\left(\dfrac{1}{3}+\dfrac{1}{13}+\dfrac{1}{11}+\dfrac{1}{6}\right)\) \(9.\left(\dfrac{1}{4}+\dfrac{1}{7}+\dfrac{1}{6}\dfrac{1}{11}\right)\)
= \(\dfrac{2}{4}X\dfrac{5}{9}\)= \(\dfrac{10}{36}\)= \(\dfrac{5}{18}\)
bạn làm kiểu này :
0.5x-\(\dfrac{2}{3}\)x=\(\dfrac{7}{6}\)
0-\(\dfrac{2}{3}\)x=\(\dfrac{7}{6}\)
\(\dfrac{2}{3}\)x=0-\(\dfrac{7}{6}\)
0.5x-\(\dfrac{2}{3}\)x=\(\dfrac{7}{6}\)
\(\left(\dfrac{1}{2}-\dfrac{2}{3}\right)\). x=\(\dfrac{7}{6}\)
\(\left(\dfrac{3}{6}-\dfrac{4}{6}\right)\). x=\(\dfrac{7}{6}\)
\(\dfrac{-1}{6}\). x=\(\dfrac{7}{6}\)
x=\(\dfrac{7}{6}\):\(\dfrac{-1}{6}\)
x=\(\dfrac{7}{6}\) . \(\dfrac{6}{-1}\)
x=\(\dfrac{42}{-6}\)
x=\(\dfrac{7}{-1}\)