Question

3, Tìm x, biết:

a) 2,5 : 7,5 = x : \(\dfrac{3}{5}\)

b) \(2\dfrac{2}{3}\) : x = \(1\dfrac{7}{9}\)

c) \(\dfrac{5}{6}\) : x = 20 : 3

Answer 1

a, \(2,5:7,5=x:\dfrac{3}{5}\)

\(\Leftrightarrow x:\dfrac{3}{5}=2,5:7,5\)

=> \(x.7,5=\dfrac{3}{5}.2,5\) => \(x=\dfrac{1,5}{7,5}=\dfrac{1}{5}\)

b, \(2\dfrac{2}{3}:x=1\dfrac{7}{9}\)

=> \(x=2\dfrac{2}{3}:1\dfrac{7}{9}\)

=> \(x=\dfrac{3}{2}\)

c, \(\dfrac{5}{6}:x=20:3\)

=> \(x.20=\dfrac{5}{6}.3\) => \(x=\dfrac{2,5}{20}=\dfrac{1}{8}\)

Answer 2

3, Tìm x, biết:

a) 2,5 : 7,5 = x : \(\dfrac{3}{5}\)

=> \(x:\dfrac{3}{5}=\dfrac{1}{3}\)

=> \(x=\dfrac{1}{3}.\dfrac{3}{5}=>x=\dfrac{1}{5}\)

b) \(2\dfrac{2}{3}\) : x = \(1\dfrac{7}{9}\)

=> \(\dfrac{8}{3}:x=\dfrac{16}{9}\)

=> \(x=\dfrac{8}{3}:\dfrac{16}{9}=>x=\dfrac{3}{2}\)

c) \(\dfrac{5}{6}\) : x = 20 : 3

=> \(x=\dfrac{5}{6}:\dfrac{20}{3}=>x=\dfrac{1}{8}\)