Question

tính bằng cách thuận tiện nhất :

3/7+4/9+4/7+5/9

Answer 1

=(3/7+4/7)+(4/9+5/9)

=1+1=2

Answer 2

\(\dfrac{3}{7}+\dfrac{4}{9}+\dfrac{4}{7}+\dfrac{5}{9}=\left(\dfrac{3}{7}+\dfrac{4}{7}\right)+\left(\dfrac{4}{9}+\dfrac{5}{9}\right)=\dfrac{7}{7}+\dfrac{9}{9}=1+1=2\)

Answer 3

=(3/7+4/7)+(5/9+4/9)=1+1=2

Answer 4

\(\left(\dfrac{3}{7}+\dfrac{4}{7}\right)+\left(\dfrac{4}{9}+\dfrac{5}{9}\right)=\dfrac{7}{7}+\dfrac{9}{9}=2\)

Answer 5

= 2