Question

Tìm y, biết:

a) \(-\dfrac{3}{5}\times y=\dfrac{21}{10}\)

b) \(y\div\dfrac{3}{8}=-1\dfrac{31}{33}\)

c) \(1\dfrac{2}{5}\times y+\dfrac{3}{7}=-\dfrac{4}{5}\)

d) \(-\dfrac{11}{12}\times y+0,25=\dfrac{5}{6}\)

Answer 1

\(a,-\dfrac{3}{5}.y=\dfrac{21}{10}\)

\(y=\dfrac{21}{10}:\dfrac{-3}{5}=\dfrac{-7}{2}\)

\(b,y:\dfrac{3}{8}=-1\dfrac{31}{33}\)

\(y=-1\dfrac{31}{33}.\dfrac{3}{8}=\dfrac{-8}{11}\)

Vậy \(y=-\dfrac{8}{11}\)

\(c,1\dfrac{2}{5}.y+\dfrac{3}{7}=-\dfrac{4}{5}\)

\(\Rightarrow1\dfrac{2}{5}y=-\dfrac{4}{5}-\dfrac{3}{7}=\dfrac{-43}{35}\)

\(\Rightarrow y=\dfrac{-43}{35}:1\dfrac{2}{5}=\dfrac{-43}{49}\)

\(d,-\dfrac{11}{12}.y+0,25=\dfrac{5}{6}\)

\(\Rightarrow-\dfrac{11}{12}.y=\dfrac{5}{6}-0,25=\dfrac{7}{12}\)

\(\Rightarrow y=\dfrac{7}{12}:\dfrac{-11}{12}=\dfrac{-7}{11}\)