Question

Thực hiện phép tính một cách hợp lí:

a) 1/7. (-3/8)+1/7. (-13/8)

b) 3/5.13/46-1/10.16/23

Answer 1

a) \(\dfrac{1}{7}.\dfrac{-3}{8}+\dfrac{1}{7}.\dfrac{-13}{8}\)

\(=\dfrac{1}{7}.\left(\dfrac{-3}{8}+\dfrac{-13}{8}\right)\)

\(=\dfrac{1}{7}.\left(-2\right)\)

\(=\dfrac{-2}{7}\)

b) \(\dfrac{3}{5}.\dfrac{13}{46}-\dfrac{1}{10}.\dfrac{16}{23}\)

\(=\dfrac{39}{230}\) - \(\dfrac{8}{115}\)

\(=\dfrac{1}{10}\)

Answer 2

a, \(\dfrac{1}{7}.\left(-\dfrac{3}{8}\right)+\dfrac{1}{7}.\left(-\dfrac{13}{8}\right)\)

=> \(\dfrac{1}{7}.\left[\left(-\dfrac{3}{8}\right)+\left(-\dfrac{13}{8}\right)\right]\)

=> \(\dfrac{1}{7}.-\dfrac{16}{8}\)

=> \(\dfrac{1}{7}.\left(-2\right)\)

=> \(\dfrac{-2}{7}\)

Answer 3

b/ \(\dfrac{1}{7}\) . ( \(\dfrac{-3}{8}\)) +\(\dfrac{1}{7}\).(\(\dfrac{-13}{8}\))

= \(\dfrac{1}{7}\) . (\(\dfrac{-3}{8}\) + \(\dfrac{-13}{8}\) )

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

=\(\dfrac{-2}{7}\)

b/ \(\dfrac{3}{5}\).\(\dfrac{13}{46}\)-\(\dfrac{1}{10}\) .\(\dfrac{16}{23}\)

= \(\dfrac{39}{230}\)-\(\dfrac{8}{115}\)

=\(\dfrac{1}{10}\)