Question

[vũ hà linh]

bài 1 : Tìm y

\(\dfrac{7}{8}xy-\dfrac{6}{4}=\dfrac{3}{2}\)                                                              \(\dfrac{2}{5}:y+\dfrac{1}{5}:y=\dfrac{10}{3}\)

bài 2 : Tính nhanh

\(\dfrac{2}{5}x\dfrac{4}{7}+\dfrac{2}{5}x\dfrac{3}{7}\)                                                                           \(\dfrac{2}{9}:\dfrac{2}{3}:\dfrac{3}{9}\)

Answer 1

[Minh Hiếu]

Bài 1:

+) \(\dfrac{7}{8}\times y=\dfrac{3}{2}+\dfrac{6}{4}=3\)

\(y=3:\dfrac{7}{8}=\dfrac{24}{7}\)

+) \(\dfrac{1}{y}\times\left(\dfrac{2}{5}+\dfrac{1}{5}\right)=\dfrac{10}{3}\)

\(\dfrac{1}{y}=\dfrac{10}{3}:\dfrac{3}{5}=\dfrac{50}{9}\)

\(y=\dfrac{9}{50}\)

Answer 2

[Minh Hiếu]

Bài 2:

+) \(=\dfrac{2}{5}\times\left(\dfrac{4}{7}+\dfrac{3}{7}\right)\)

\(=\dfrac{2}{5}\times\dfrac{7}{7}=\dfrac{2}{5}\)

+) \(\dfrac{2}{9}:\dfrac{2}{3}:\dfrac{3}{9}\)

\(\dfrac{2}{9}\times\dfrac{3}{2}\times\dfrac{9}{3}=1\)