Trả lời :

\(a,\frac{3}{2}\times\left(\frac{5}{7}-\frac{4}{3}\right)-\frac{4}{3}\times\left(\frac{5}{7}-\frac{3}{2}\right)\)

\(=\frac{3}{2}\times\frac{5}{7}-\frac{3}{2}\times\frac{4}{3}-\frac{4}{3}\times\frac{5}{7}+\frac{4}{3}\times\frac{3}{2}\)

\(=\frac{3}{2}\times\frac{5}{7}-\frac{4}{3}\times\frac{5}{7}\)

\(=\frac{5}{7}\times\left(\frac{3}{2}-\frac{4}{3}\right)\)

\(=\frac{5}{42}\)

b, Tương tự câu a. Kết quả \(=-\frac{3}{7}\)

Đúng y như kết quả của mình làm

`@` `\text {Ans}`

`\downarrow`

`a)`

\(\dfrac{3}{4}+\dfrac{2}{3}+\dfrac{3}{5}\)

`=`\(\dfrac{9}{12}+\dfrac{8}{12}+\dfrac{3}{5}\)

`=`\(\dfrac{17}{12}+\dfrac{3}{5}\)

`=`\(\dfrac{85}{60}+\dfrac{36}{60}\)

`=`\(\dfrac{121}{60}\)

`b)`

\(\dfrac{1}{2}\cdot\dfrac{9}{13}\div\dfrac{27}{26}\)

`=`\(\dfrac{1}{2}\cdot\dfrac{9}{13}\cdot\dfrac{26}{27}\)

`=`\(\dfrac{1}{2}\cdot\dfrac{2}{3}\)

`=`\(\dfrac{1}{3}\)

`c)`

\(\dfrac{2}{7}\cdot\dfrac{1}{9}+\dfrac{2}{7}\cdot\dfrac{2}{9}+\dfrac{1}{3}\cdot\dfrac{5}{7}\)

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

`=`\(\dfrac{2}{7}\cdot\dfrac{1}{3}+\dfrac{1}{3}\cdot\dfrac{5}{7}\)

`=`\(\dfrac{1}{3}\cdot\left(\dfrac{2}{7}+\dfrac{5}{7}\right)\)

`=`\(\dfrac{1}{3}\cdot1=\dfrac{1}{3}\)

`d)`

\(11\div\dfrac{5}{2}+11\div\dfrac{7}{3}+11\div\dfrac{35}{6}\)

`=`\(11\cdot\dfrac{2}{5}+11\cdot\dfrac{3}{7}+11\cdot\dfrac{6}{35}\)

`=`\(11\cdot\left(\dfrac{2}{5}+\dfrac{3}{7}+\dfrac{6}{35}\right)\)

`=`\(11\cdot1=11\)

a) 3/4 + 2/3 + 3/5 = 45/60 + 40/60 + 36/60 = 121/60

b) 1/2 x 9/13 : 27/26 = 9/26 x 26/27 = 1/3

c) 2/7 x 1/9 + 2/7 x 2/9 + 1/3 x 5/7 = 2/7 x (1/9 + 2/9) + 5/21 = 2/7 x 1/3 + 5/21 = 2/21 + 5/21 = 1/3

d) 11 : 5/2 + 11 : 7:3 + 11 : 35/6 = 11 x (2/5 + 3/7 + 6/35) = 11 x 1 = 11 

C>D thì phải

hoặc C<D

chọn 1 trong2

2/3 + 3/4=17/12
9/4 + 3/5=57/20
5/24 + 1/4=11/24
3/15 - 5/35=2/35        18/27 - 2/6=1/3        37/12 - 3=1/12
11/9 x 3/22=1/6         7/13 x 13/7=1       4 x6/7=24/7
2/5 : 3/10=4/3           3/8 : 9/4=1/6            8/21 : 4/7=2/3

2/3 + 3/4

= 17/12
9/4 + 3/5

= 57/20
5/24 + 1/4

=11/24
3/15 - 5/35   

=2/35   

18/27 - 2/6   

=1/3   

37/12 - 3

= 1/12
11/9 x 3/22 

=1/6       

7/13 x 13/7 

=1   

 4 x6/7

=24/7
2/5 : 3/10

=4/3         

 3/8 : 9/4   

=1/6       

8/21 : 4/7

= 2/3

1=17/12
2=57/20
3=11/24
4=2/35        7=1/3        10=1/12
5=1/6         8=1       11=24/7

6=4/3           9=1/6            12=2/3

a/

$\frac{7}{4}+\frac{9}{16}=\frac{28}{16}+\frac{9}{16}=\frac{28+9}{16}=\frac{37}{16}$

b/

$\frac{-70}{27}+\frac{35}{9}=\frac{-70}{27}+\frac{105}{27}=\frac{35}{27}$

c/

$\frac{-4}{-5}+\frac{-2}{3}=\frac{4}{5}-\frac{2}{3}=\frac{12}{15}-\frac{10}{15}=\frac{2}{15}$

d/ Đề thiếu. Bạn xem lại.

i/

$\frac{-7}{2}+(\frac{-5}{-4}-\frac{4}{-9}$

$=\frac{-7}{2}+\frac{5}{4}+\frac{4}{9}$

$=\frac{-14}{4}+\frac{5}{4}+\frac{4}{9}$

$=\frac{-9}{4}+\frac{4}{9}=\frac{-81}{36}+\frac{16}{36}=\frac{-65}{36}$

k/

$\frac{1}{4}+\frac{1}{3}-\frac{1}{2}$

$=\frac{3}{12}+\frac{4}{12}-\frac{6}{12}=\frac{1}{12}$

m/

$\frac{-1}{9}-\frac{1}{7}-\frac{3}{4}$

$=-(\frac{1}{9}+\frac{1}{7}+\frac{3}{4})$

$=-(\frac{28}{252}+\frac{36}{252}+\frac{189}{252})$

$=\frac{-253}{252}$

n/

$\frac{11}{12}-(\frac{-3}{18}+\frac{5}{6}$

$=\frac{11}{12}+\frac{1}{6}+\frac{5}{6}$

$=\frac{11}{12}+1=\frac{23}{12}$

o/

$\frac{20}{17}+\frac{-11}{2}-\frac{30}{4}$

$=\frac{20}{17}-\frac{11}{2}-\frac{15}{2}$

$=\frac{20}{7}-13=\frac{-71}{7}$

v/

$\frac{1}{2}-\frac{3}{4}+\frac{5}{6}$

$=\frac{6}{12}-\frac{9}{12}+\frac{10}{12}$

$=\frac{6-9+10}{12}=\frac{7}{12}$

e/

$\frac{-2}{3}-\frac{1}{7}+(\frac{-6}{2})$

$=-(\frac{2}{3}+\frac{1}{7})-3$

$=-\frac{17}{21}-3=-\frac{80}{21}$

f/

$\frac{-4}{5}+\frac{3}{10}-\frac{2}{-15}$

$=\frac{-24}{30}+\frac{9}{30}+\frac{4}{30}$

$=\frac{-11}{30}$

g/

$=\frac{20}{21}+\frac{133}{21}-\frac{36}{21}$

$=\frac{117}{21}=\frac{39}{7}$

h/

$=\frac{1}{4}-\frac{14}{4}+\frac{3}{11}$

$=\frac{-13}{4}+\frac{3}{11}=\frac{-131}{44}$

y/

$=-(\frac{9}{4}+\frac{1}{7}+\frac{12}{7})$

$=-(\frac{9}{4}+\frac{13}{7})=-\frac{115}{28}$

BT1 :thực hành phép tính

4/3+-11/31+3/10-20/31-2/5 = 7/30

7/12-1/-16+3/4 = 67/48

2/11.-5/4+-9/11.5/4+ 1 và 3/4 = -1/4 * và 3/4 là sao bạn *

-9/27-25/75 = -2/3