Question

Áp dụng tính: \(\dfrac{1}{30}+\dfrac{1}{42}+\dfrac{1}{56}\)

Help Me!!

Answer 1

\(\dfrac{1}{30}+\dfrac{1}{42}+\dfrac{1}{56}\)

=\(\dfrac{1}{5.6}+\dfrac{1}{6.7}+\dfrac{1}{7.8}\)

=\(\dfrac{1}{5}-\dfrac{1}{6}+\dfrac{1}{6}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{8}\)

=\(\dfrac{1}{5}-\dfrac{1}{8}\)

=\(\dfrac{3}{40}\)

Answer 2

áp dụng cái gì để tính...

Answer 3

=\(\dfrac{1}{5.6}+\dfrac{1}{6.7}+\dfrac{1}{7.8}\)=\(\dfrac{1}{5}-\dfrac{1}{6}+\dfrac{1}{6}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{8}\)=\(\dfrac{1}{5}-\dfrac{1}{8}\)=\(\dfrac{8}{40}+\dfrac{5}{40}=\dfrac{13}{40}\)

Answer 4

tick cho mk nha