Tính A rồi so sánh:

\(\frac{1}{4}\) + \(\frac{1}{9}\) + \(\frac{1}{16}\) + \(\frac{1}{25}\) + \(\frac{1}{36}\) = \(\frac{1769}{3600}\)

3600 chia hết cho 6, nên ta chọn 3600 làm mẫu số chung.

3600 : 6 = 600

\(\frac{5}{6}\) = \(\frac{5\times600}{6\times600}\) = \(\frac{3000}{3600}\)

Mà \(\frac{3000}{3600}\) > \(\frac{1769}{3600}\)

Nên: \(\frac{5}{6}\) > A

a)    \(\frac{5}{11}+\frac{6}{25}+\frac{66}{121}\)

\(=\left(\frac{5}{11}+\frac{66}{121}\right)+\frac{6}{25}\)

\(=1+\frac{6}{25}\)

\(=\frac{31}{25}\)

12/5 -4/5 =8/5

11/6 -2/3 =21/18 =7/6

7/8 -2/7 =33/56

4 -8/5 =20/5-8/5 =12/5

2 -3/8 =16/8 -3/8 =13/8

16/7 -2 =16/7 -14/7 =2/7

25/4 -3=25/4 -12/4 =13/4

câu 2 :                                       câu 3 :

a) 8/5                                         a)4 - 8/5 = 20/5 - 8/5 =12/5

b) 7/6                                         b)2 - 3/8 =16/8 - 3/8 = 13/8 

c) 35/56                                      c)16/7 - 2 = 16/7 - 14/7 = 2/7

                                                  d)25/4 - 3 = 25/4 - 12/4 = 13/4

\(\frac{9}{8}>\frac{8}{9}\)

\(\frac{16}{23}>\frac{16}{25}\)

\(\frac{8}{11}< \frac{8}{10}\)

\(\frac{10}{13}>\frac{19}{26}\)

\(\frac{13}{15}< \frac{11}{10}\)

\(\frac{11}{9}=\frac{44}{36}\)

9/8 > 8/9 

16/23 > 16/25 

8/11 < 8/10 

10/13 > 19/26 

13/15 < 11/10 

11/9 = 44/36 

Tham khảo nha !

Chúc bạn học giỏi !

\(\frac{8}{5}-\frac{18}{27}\)

\(=\frac{8}{5}-\frac{2}{3}\)

\(=\frac{24}{15}-\frac{10}{15}\)

\(=\frac{14}{15}\)

\(\frac{12}{20}-\frac{6}{18}\)

\(=\frac{3}{5}-\frac{1}{3}\)

\(=\frac{9}{15}-\frac{5}{15}\)

\(=\frac{4}{15}\)

\(\frac{8}{24}-\frac{5}{25}\)

\(=\frac{1}{3}-\frac{1}{5}\)

\(=\frac{5}{15}-\frac{3}{15}\)

\(=\frac{2}{15}\)

\(\frac{18}{21}-\frac{12}{27}\)

\(=\frac{6}{7}-\frac{4}{9}\)

\(=\frac{54}{63}-\frac{28}{63}\)

\(=\frac{26}{63}\)

1)8/5-2/3=14/15

2)3/5-1/3=4/15

3)1/3-1/5=2/15

4)6/7-4/9=26/63

đáp án là B

ý B nhé bạmn

câu 1: 0

\(\frac{24}{36}\)

a )

2 / 3 + 5 / 4 = 8 / 12 + 15 / 12 = 23 / 12

b )

15 / 25 + 6 / 21 = 3 / 5 + 2 / 7 

                       = 21 / 35 + 10 / 35

                       = 31 / 35

c ) 

4 / 3 - 11 / 15 = 20 / 15 - 11 / 15

                    = 9 / 15

d )

12 / 10 - 2 / 5 = 12 / 10 - 4 / 10

                    = 8 / 10

                    = 4 / 5

a=23/12

b=31/35

c=3/5

d=4/5

\(\frac{3}{4}.\frac{8}{9}.\frac{15}{16}.\frac{24}{25}.\frac{35}{36}\)

\(=\frac{3.2.4.3.5.4.6.5.7}{2.2.3.3.4.4.5.5.6.6}=\frac{7}{2.6}\)

\(=\frac{7}{12}\)

\(=\frac{1\cdot3\cdot2\cdot4\cdot3\cdot5\cdot4\cdot6\cdot5\cdot7}{2\cdot2\cdot3\cdot3\cdot4\cdot4\cdot5\cdot5\cdot6\cdot6}\)  

\(=\frac{1\cdot7}{2\cdot6}\)   

\(=\frac{7}{12}\)