Question

Tìm x biết:

\(\dfrac{4}{7}+\dfrac{3}{7}:x=-5\)

b)\(\dfrac{-1}{2}x+\dfrac{2}{3}.\dfrac{-5}{4}=\dfrac{3}{5}-\dfrac{5}{6}\)

Answer 1

\(a)\dfrac{4}{7}+\dfrac{3}{7}\div x=-5\)

\(\dfrac{3}{7}\div x=\left(-5\right)-\dfrac{4}{7}\)

\(\dfrac{3}{7}\div x=\dfrac{-39}{7}\)

\(x=\dfrac{3}{7}\div\dfrac{-39}{7}\)

\(x=\dfrac{-1}{13}\)

\(Vậy\) \(x=\dfrac{-1}{13}\)

\(b)\dfrac{-1}{2}\times x+\dfrac{2}{3}\times\dfrac{-5}{4}=\dfrac{3}{5}-\dfrac{5}{6}\)

\(\dfrac{-1}{2}\times x+\dfrac{-5}{6}=\dfrac{-7}{30}\)

\(\dfrac{-1}{2}\times x=\dfrac{-7}{30}-\dfrac{-5}{6}\)

\(\dfrac{-1}{2}\times x=\dfrac{3}{5}\)

\(x=\dfrac{3}{5}\div\dfrac{-1}{2}\)

\(x=\dfrac{-6}{5}\)

\(Vậy\) \(x=\dfrac{-6}{5}\)

Answer 2

\(\dfrac{4}{7}+\dfrac{3}{7}:x=-5\\ \dfrac{3}{7}:x=-5-\dfrac{4}{7}\\ \dfrac{3}{7}:x=\dfrac{-39}{7}\\ x=\dfrac{3}{7}:\dfrac{-39}{7}\\ x=\dfrac{-1}{13}\)