\(\frac{5}{7}+\frac{5}{14}+\frac{5}{28}+\frac{5}{56}+\frac{5}{112}+\frac{5}{224}+\frac{5}{448}+\frac{5}{896}\)

\(=(\frac{5}{7}+\frac{5}{14})+(\frac{5}{28}+\frac{5}{56})+(\frac{5}{112}+\frac{5}{224})+(\frac{5}{448}+\frac{5}{896})\)

\(=\frac{15}{14}+\frac{15}{56}+\frac{15}{224}+\frac{15}{896}\)

\(=(\frac{15}{14}+\frac{15}{224})+(\frac{15}{56}+\frac{15}{896})\)

\(=\frac{255}{224}+\frac{255}{896}=\frac{1275}{896}\)

Rồi tự rút gọn nhé . Nếu số đó ko rút gọn được thì giữ nguyên

Chúc bạn học tốt :>

B

B

B

70 : 7 = 10

28 : 7 =4

30 : 6 = 5

8 : 2 = 9

63 : 7 = 9

42 : 6 = 7

35 : 5 = 6

27 : 3 = 9

14 : 7 = 2

42 : 7 = 6

35 : 7 = 5

56 : 7 = 8.

hruyhy835y6n./ reuy786y7866

280 nho like cho minh nhe

Ta có:56x2+28x5 +28

=28x2x2+28x5+28

=28x4+28x5+28

=28x(4+5+1)

=28x10=280

56 x 2 + 28 x 5 + 28
       = 28 x 2 x 2 + 28 x 5 + 28 x 1
       = 28 x 4 + 28 x 5 + 28 x 1
       = 28 x ( 4 + 5 + 1 )
       = 28 x 10
       = 280

\(\dfrac{-3}{5}+\dfrac{28}{5}.\left(\dfrac{43}{56}+\dfrac{5}{24}-\dfrac{21}{63}\right)\)

= \(\dfrac{-3}{5}+\dfrac{28}{5}.\dfrac{9}{14}\)

= \(\dfrac{-3}{5}+\dfrac{28.9}{5.14}\)

= \(\dfrac{-3}{5}+\dfrac{18}{5}\)

= \(\dfrac{\left(-3\right)+18}{5}\)

= \(\dfrac{15}{5}=3\)

36255