Question

[chachah1]

Tính bằng cách thuận tiện nhất

2/7 + 1/5 + 0,2 x 4/7

Answer 1

[HT.Phong (9A5)]

\(\dfrac{2}{7}\times\dfrac{1}{5}+0,2\times\dfrac{4}{7}\)

\(=\dfrac{2}{7}\times\dfrac{1}{5}+\dfrac{1}{5}\times\dfrac{4}{7}\)

\(=\dfrac{1}{5}\times\left(\dfrac{2}{7}+\dfrac{4}{7}\right)\)

\(=\dfrac{1}{5}\times\dfrac{6}{7}\)

\(=\dfrac{6}{35}\)