Tích trên bằng:

14/15x5/24x48/7=4/3

Đáp số: 4/3

14/15x5/24x48/7=4/3

Chúc bạn học giỏi nha!!!

Tích trên  bằng:

14/15x5/24x48/7=4/3

Đáp số: 4/3

B

a.9/20-8/15x5/12

=9/20-2/9

=41/180

b.2/3:4/5:7/12

=5/6:7/12

=10/7

c.4/9+11/8-5/6

=131/72-5/6

=71/72

tk mk nhé bạn

39/180

120/84

71/72

9/20 - 8/15 x 5/12 = 9/20 - 2/9

                             = 81/180 - 40/180

                             = 41/180

2/3  : 4/5 : 7/12 = 2/3 x 5/4 : 7/12

                         = 5/6 : 7/12

                         = 5/6 x 12/7

                         = 10/7

4/9 + 11/8 - 5/6 = 32/72 + 99/72 - 60/72

                         = 71/72

?????????? sai đề hả                                                                                                 THÙY DUONG

tên đăng nhập là gì

\(\left(-\dfrac{7}{23}\right).\left(\dfrac{13}{28}\right)+\left(-\dfrac{7}{23}\right).\left(\dfrac{25}{28}\right)\)

\(=\left(-\dfrac{7}{23}\right).\left(\dfrac{13}{28}+\dfrac{25}{28}\right)\)

\(=\left(-\dfrac{7}{23}\right).\left(\dfrac{38}{28}\right)\)

\(=\left(-\dfrac{7}{23}\right).\left(\dfrac{19}{14}\right)\)

\(=-\dfrac{19}{46}\)

\(\left(-\dfrac{7}{23}\right)\cdot\left(\dfrac{13}{28}\right)+\left(-\dfrac{7}{13}\right)\cdot\left(\dfrac{25}{28}\right)\)

\(=\left(-\dfrac{7}{23}\right)\cdot\left(\dfrac{13}{28}+\dfrac{25}{28}\right)\)

\(=\left(-\dfrac{7}{13}\right)\cdot\dfrac{38}{28}\)

\(=\left(-\dfrac{7}{13}\right)\cdot\dfrac{19}{14}\)

\(=-\dfrac{19}{26}\)

Ta có : 

\(\dfrac{4}{5}=\dfrac{140}{175};\dfrac{28}{5}=\dfrac{196}{175};\dfrac{28}{7}=\dfrac{700}{175};\dfrac{25}{25}=\dfrac{175}{175};\dfrac{2}{5}=\dfrac{70}{175}\\ \dfrac{70}{175}< \dfrac{140}{175}< \dfrac{175}{175}< \dfrac{700}{175}< \dfrac{980}{175}\\ \Rightarrow\dfrac{2}{5}< \dfrac{4}{5}< \dfrac{25}{25}< \dfrac{28}{7}< \dfrac{28}{5}\)

2/5,4/5,25/25,28/7,28/5

=15 * ( 2 + 3 -5 ) rồi bạn tự hiểu nhé

15x (2 + 3 - 5) =

15x 0 = 0

15x2+15x3-15x5

=15x(2+3-5)

=15x0

=0

k mik nhé bn