Question

1. tìm x

a.\(\dfrac{1}{5}+x=\dfrac{13}{30}\)

b.\(\dfrac{1}{6}-x=\dfrac{5}{12}\)

c. \(x.\left(\dfrac{-1^{ }}{2}\right)^2=\dfrac{1}{16}\)

d. \(x:\dfrac{7}{11}=\dfrac{9}{33}\)

e. \(\dfrac{3}{5}.x=\dfrac{-21}{10}\)

Answer 1

1)

a.\(\dfrac{1}{5}+x=\dfrac{13}{50}\)

\(\Leftrightarrow x=\dfrac{13}{50}-\dfrac{1}{5}=\dfrac{13-10}{50}=\dfrac{3}{50}\)

b.\(\dfrac{1}{6}-x=\dfrac{5}{12}\)

\(\Leftrightarrow x=\dfrac{1}{6}-\dfrac{5}{12}=\dfrac{2-5}{12}=-\dfrac{3}{12}=-\dfrac{1}{4}\)

c.\(x\left(-\dfrac{1}{2}\right)^2=\dfrac{1}{16}\)

\(\Leftrightarrow x\left(-\dfrac{1}{2}\right)^2=\dfrac{1}{4}.\left(-\dfrac{1}{2}\right)^2\)

\(\Leftrightarrow x=\dfrac{1}{4}\)

d.\(x:\dfrac{7}{11}=\dfrac{9}{33}\)

\(\Leftrightarrow x=\dfrac{9}{33}.\dfrac{7}{11}=\dfrac{3}{11}.\dfrac{7}{11}=\dfrac{21}{121}\)

e.\(\dfrac{3}{5}.x=-\dfrac{21}{10}\)

\(\Leftrightarrow x=-\dfrac{21}{10}:\dfrac{3}{5}=-\dfrac{21}{10}.\dfrac{5}{3}=-\dfrac{7}{2}\)