Question

Tính:

1, -1/5- (-2/3 )

2, -2/5- 1/7

3, 3/5- 5/7

4, 4/7+ -5/8 - 3/28

Answer 1

1. \(-\dfrac{1}{5}-\left(-\dfrac{2}{3}\right)=\dfrac{-1}{5}+\dfrac{2}{3}=\dfrac{7}{15}.\)

2. \(-\dfrac{2}{5}-\dfrac{1}{7}=\dfrac{-14-5}{35}=\dfrac{-19}{35}.\)

3. \(\dfrac{3}{5}-\dfrac{5}{7}=\dfrac{21-25}{35}=\dfrac{-4}{35}.\)

4. \(\dfrac{4}{7}+\dfrac{-5}{8}-\dfrac{3}{28}=\dfrac{32-35-6}{56}=\dfrac{-9}{56}.\)

Answer 2

1: \(=\dfrac{-1}{5}+\dfrac{2}{3}=\dfrac{-3+10}{15}=\dfrac{7}{15}\)

2: \(=\dfrac{-14}{35}-\dfrac{5}{35}=-\dfrac{19}{35}\)

3: \(=\dfrac{21}{35}-\dfrac{25}{35}=-\dfrac{4}{35}\)

4: \(=\dfrac{32}{56}-\dfrac{35}{56}-\dfrac{6}{56}=\dfrac{-9}{56}\)