a: 90/126=5/7<6/7

b: 70/84=5/6

35/42=5/6

=>70/84=35/42

a)\(\dfrac{90}{126}=\dfrac{5}{7}< \dfrac{6}{7}\Leftrightarrow\cdot\dfrac{90}{126}< \dfrac{6}{7}\)

b)\(\dfrac{70}{84}=\dfrac{5}{6};\dfrac{35}{42}=\dfrac{5}{6}\Leftrightarrow\cdot\dfrac{70}{84}=\dfrac{35}{42}\)

Bài 1:

\(\frac{90}{126}=\frac{5}{7};\frac{6}{7}=\frac{6}{7}\)

\(\frac{90}{126}=\frac{5}{7};\frac{35}{49}=\frac{5}{7}\)

Bài 2:

ta có: 8/9 = 0,8888

19/20 = 0,95

10/11 = 0,9090

21/22 = 0,9595

=> 21/22 là phân số lớn nhất

\(\frac{90}{126}=\frac{90:18}{126:18}=\frac{5}{7}\\ \frac{35}{49}=\frac{35:7}{49:7}=\frac{5}{7}\\\frac{5}{7}=\frac{5}{7}\\ =>\frac{90}{126}=\frac{35}{49}\)

k mik nhé m.n

Ta nhận thấy cả 2 phân số đều chưa tối giản. Vậy cần rút gọn

\(\frac{90}{126}=\frac{5}{7};\frac{35}{49}=\frac{5}{7}\)

Mà: \(\frac{5}{7}=\frac{5}{7}\)

\(\Rightarrow\frac{90}{126}=\frac{35}{49}\)

D

D

D

\(\dfrac{90}{126}=\dfrac{90:18}{126:18}=\dfrac{5}{7}\)

D

D.5 phần 7

a)36/48>12/48

=>6/8>3/12

b)135/225<180/225

=>15/25<36/45

c)1575/2835>1323/2835

=>15/27>49/105

Chúc e học tốt

a) mẫu số chung: 4

\(\dfrac{6}{8}=\dfrac{6:2}{8:2}=\dfrac{3}{4};\dfrac{3}{12}=\dfrac{3:3}{12:3}=\dfrac{1}{4}\)

vì \(\dfrac{3}{4}>\dfrac{1}{4}\)nên \(\dfrac{6}{8}>\dfrac{3}{12}\)

b) mẫu số chung: 5

\(\dfrac{15}{25}=\dfrac{15:5}{25:5}=\dfrac{3}{5};\dfrac{36}{45}=\dfrac{36:9}{45:9}=\dfrac{4}{5}\)

vì\(\dfrac{3}{5}< \dfrac{4}{5}\)nên \(\dfrac{15}{25}< \dfrac{36}{45}\)

a) 

\(\dfrac{6}{12}=\dfrac{6:6}{12:6}=\dfrac{1}{2}\)

\(\Rightarrow\dfrac{1}{2}=\dfrac{1\times2}{2\times2}=\dfrac{2}{4}\)

Mà \(\dfrac{2}{4}< \dfrac{3}{4}\)

Vậy \(\dfrac{6}{12}< \dfrac{3}{4}\).

b)

\(\dfrac{8}{10}=\dfrac{8:2}{10:2}=\dfrac{4}{5}\)

Mà \(\dfrac{2}{5}< \dfrac{4}{5}\)

Vậy \(\dfrac{2}{5}< \dfrac{8}{10}\).

c)

\(\dfrac{40}{35}=\dfrac{40:5}{35:5}=\dfrac{8}{7}\)

Mà \(\dfrac{8}{7}>\dfrac{6}{7}\)

Vậy \(\dfrac{40}{35}>\dfrac{6}{7}\).

d)

\(\dfrac{8}{16}=\dfrac{8:8}{16:8}=\dfrac{1}{2}\)

Mà \(\dfrac{1}{2}< \dfrac{5}{2}\)

Vậy \(\dfrac{8}{16}< \dfrac{5}{2}\).

`40/35= 8/7`

`8=8->40/35=8/7`

\(\frac{16}{48}=\frac{16:16}{48:16}=\frac{1}{3}\);\(\frac{14}{35}=\frac{14:7}{35:7}=\frac{2}{5}\)

\(\frac{1}{3}=\frac{1\cdot5}{3\cdot5}=\frac{5}{15}\);    \(\frac{2}{5}=\frac{2\cdot3}{5\cdot3}=\frac{6}{15}\)