bài 3
a)\(x=\dfrac{-1}{4}+\dfrac{2}{13}\)
\(x=\dfrac{-13}{52}+\dfrac{8}{52}\)
\(x=\)\(\dfrac{-5}{52}\)
b)\(\dfrac{X}{3}=\dfrac{2}{3}+\dfrac{-1}{7}\)
\(\dfrac{X}{3}=\dfrac{14}{21}+\dfrac{-3}{21}\)
\(\dfrac{X}{3}=\dfrac{11}{21}\)
\(\Rightarrow\)\(X\times21=11\times3\)
\(\Rightarrow\)\(X\times21=33\)
\(\Rightarrow\)\(X=33\div21\)
\(\Rightarrow\)\(X=\dfrac{11}{7}\)
c)\(\dfrac{-5}{6}-x=\dfrac{7}{12}+\dfrac{-1}{3}\)
\(\dfrac{-5}{6}-x=\dfrac{7}{12}+\dfrac{-4}{12}\)
\(\dfrac{-5}{6}-x=\dfrac{1}{4}\)
\(x=\dfrac{-5}{6}-\dfrac{1}{4}\)
\(x=\dfrac{-20}{24}-\dfrac{6}{24}\)
\(x=\dfrac{-12}{13}\)
d)\(5\left(x-3\right)=\dfrac{5}{7}\)
\(x-3=\dfrac{5}{7}\div5\)
\(x-3=\dfrac{5}{7}\times\dfrac{1}{5}\)
\(x-3=\dfrac{1}{7}\)
\(x=\dfrac{1}{7}+\dfrac{3}{1}\)
\(x=\dfrac{1}{7}+\dfrac{21}{7}\)
\(x=\dfrac{22}{7}\)
e)\(-4\left(x-\dfrac{1}{3}\right)=\dfrac{-8}{3}\)
\(x-\dfrac{1}{3}=\dfrac{-8}{3}\div\dfrac{-4}{1}\)
\(x-\dfrac{1}{3}=\dfrac{-8}{3}\times\dfrac{-1}{4}\)
\(x-\dfrac{1}{3}=\dfrac{2}{3}\)
\(x=\dfrac{2}{3}+\dfrac{1}{3}\)
\(x=\dfrac{3}{3}=1\)
f)\(x+\dfrac{2}{3}=-\dfrac{1}{12}\times\dfrac{-4}{5}\)
\(x+\dfrac{2}{3}=\dfrac{-1}{12}\times\dfrac{-4}{5}\)
\(x+\dfrac{2}{3}=\dfrac{1}{15}\)
\(x=\dfrac{1}{15}-\dfrac{2}{3}\)
\(x=\dfrac{1}{15}-\dfrac{10}{15}\)
\(x=\dfrac{-3}{5}\)
g) \(x-4=\dfrac{-14}{35}:\dfrac{7}{5}\)
\(x-4=\dfrac{-14}{35}\times\dfrac{5}{7}\)
\(x-4=\dfrac{-2}{7}\)
\(x=\dfrac{-2}{7}+\dfrac{4}{1}\)
\(x=\dfrac{-2}{7}+\dfrac{28}{7}\)
\(x=\dfrac{26}{7}\)
h)\(\dfrac{-3}{7}x=\dfrac{3}{56}\times\dfrac{28}{9}\)
\(\dfrac{-3}{7}x=\dfrac{1}{6}\)
\(x=\dfrac{1}{6}:\dfrac{-3}{7}\)
\(x=\dfrac{1}{6}\cdot\dfrac{-7}{3}\)
\(x=\dfrac{-7}{18}\)
i)\(\dfrac{1}{4}x-\dfrac{7}{5}=\dfrac{-5}{8}:\dfrac{15}{4}\)
\(\dfrac{1}{4}x-\dfrac{7}{5}=\dfrac{-5}{8}\cdot\dfrac{4}{15}\)
\(\dfrac{1}{4}x-\dfrac{7}{5}=\dfrac{-1}{6}\)
\(\dfrac{1}{4}x=\dfrac{-1}{6}+\dfrac{7}{5}\)
\(\dfrac{1}{4}x=\dfrac{-5}{30}+\dfrac{42}{30}\)
\(\dfrac{1}{4}x=\dfrac{37}{30}\)
\(x=\dfrac{37}{30}:\dfrac{1}{4}\)
\(x=\dfrac{37}{30}\cdot\dfrac{4}{1}\)
\(x=\dfrac{74}{15}\)
Bài 4
A)\(x-\dfrac{3}{10}=\dfrac{7}{15}:\dfrac{3}{5}\)
\(x-\dfrac{3}{10}=\dfrac{7}{15}\cdot\dfrac{5}{3}\)
\(x-\dfrac{3}{10}=\dfrac{7}{9}\)
\(x=\dfrac{7}{9}+\dfrac{3}{10}\)
\(x=\dfrac{70}{90}+\dfrac{27}{90}\)
\(x=\dfrac{97}{90}\)
B)\(x+\dfrac{3}{22}=\dfrac{27}{121}\cdot\dfrac{11}{9}\)
\(x+\dfrac{3}{22}=\dfrac{3}{11}\)
\(x=\dfrac{3}{11}-\dfrac{3}{22}\)
\(x=\dfrac{6}{22}-\dfrac{3}{22}\)
\(x=\dfrac{3}{22}\)
c)\(\dfrac{8}{23}\cdot\dfrac{46}{24}=\dfrac{1}{3}\cdot x\)
\(\dfrac{2}{3}=\dfrac{1}{3}\cdot x\)
\(\dfrac{2}{3}:\dfrac{1}{3}\)\(=x\)
\(\dfrac{2}{3}\cdot\dfrac{3}{1}=x\)
\(\dfrac{2}{1}=x\)
d)\(\dfrac{1}{5}:x=\dfrac{1}{5}-\dfrac{1}{7}\)
\(\dfrac{1}{5}:x=\dfrac{7}{35}-\dfrac{5}{35}\)
\(\dfrac{1}{5}:x=\dfrac{2}{35}\)
\(x=\dfrac{1}{5}:\dfrac{2}{35}\)
\(x=\dfrac{1}{5}\cdot\dfrac{35}{2}\)
\(x=\dfrac{7}{2}\)
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