Question

Bài 1: thực hiện phép tính:

 \(\dfrac{2}{5}\)-\(\dfrac{1}{7}\).\(\dfrac{1}{2}\)

Answer 1

\(=\dfrac{2}{5}-\dfrac{1}{14}=\dfrac{28-5}{70}=\dfrac{23}{70}\)

Answer 2

\(=\dfrac{2}{5}-\dfrac{1}{14}=\dfrac{23}{70}\)

Answer 3

\(\dfrac{2}{5}-\dfrac{1}{7}.\dfrac{1}{2}=\dfrac{2}{5}-\dfrac{1}{14}=\dfrac{2}{5}+-\dfrac{1}{14}=\dfrac{28}{70}+-\dfrac{5}{70}=\dfrac{23}{70}\)