`@`$kudo$

Bài 1:

a)

`6/15` `=` $\dfrac{6 : 3}{15 : 3}$ `=` `2/5`

`9/36` `=` $\dfrac{9 : 9}{36 : 9}$ `=` `1/4`

`77/88` `=` $\dfrac{77 : 11}{88 : 11}$ `=` `7/8`

`15/85` `=` $\dfrac{15 : 5}{85 : 5}$ `=` `3/17`

`16/48` `=` $\dfrac{16 : 16}{48 : 16}$ `=` `1/3`

`21/63` `=` $\dfrac{21 : 21}{63 : 21}$ `=` `1/3`

`37/111` `=` $\dfrac{37 : 37}{111 : 37}$ `=` `1/3`

b)

`666/999` `=` $\dfrac{666 : 333}{999 : 333}$ `=` `2/3`

`4000/6000` `=` $\dfrac{4000 : 2000}{6000 : 2000}$ `=` `2/3`

`500/1000` `=` $\dfrac{500 : 500}{1000 : 500}$ `=` `1/2`

`15/1515` `=` $\dfrac{15 : 15}{1515}$ `=` `1/101`

`201201/119119` `=` $\dfrac{201201 : 1001}{119119 : 1001}$ `=` `201/119`

Bài 2:

a. Các phân số tối giản là: `12/21` `;` `4/9` `;` `17/13`

b. Các phân số chưa tối giản là: `36/63` `;` `48/84` `;` `56/24`

Bước rút gọn phân số:

`36/63` `=` $\dfrac{36 : 9}{63 : 9}$ `=` `4/7`

`48/84` `=` $\dfrac{48 : 12}{84 : 12}$ `=` `4/7`

`56/24` `=` $\dfrac{56 : 8}{24 : 8}$ `=` `7/3`

Bài 3:

`10/25` `=` $\dfrac{10 : 5}{25 : 5}$ `=` `2/5`

`14/18` `=` $\dfrac{14 : 2}{18 : 2}$ `=` `7/9`

`15/20` `=` $\dfrac{15 : 5}{20 : 5}$ `=` `3/4`

`16/40` `=` $\dfrac{16 : 8}{40 : 8}$ `=` `2/5`

`36/48` `=` $\dfrac{36 : 12}{48 : 12}$ `=` `3/4`

`63/81` `=` $\dfrac{63 : 9}{81 : 9}$ `=` `7/9`

`->` `10/25` `=` `16/40` `;` `14/18` `=` `63/81` `;` `15/20` `=` `36/48`

Bài 4:

a. Những phân số tối giản là: `4/9` `;` `17/13` 

b. Những phân số bằng `4/7` là: `12/21` `;` `36/63` `;` `48/84`

`12/21` `=` $\dfrac{12 : 3}{21 : 3}$ `=` `4/7` ( chọn )

`36/63` `=` $\dfrac{36 : 9}{63 : 9}$ `=` `4/7` ( chọn )

`48/84` `=` $\dfrac{48 : 12}{84 : 12}$ `=` `4/7` ( chọn )

`56/24` `=` $\dfrac{56 : 8}{24 : 8}$ `=` `7/3`

`33/77` `=` $\dfrac{33 : 11}{77 : 11}$ `=` `3/7`

Xin hay nhất

∘∘kudokudo

Bài 1:

a)

615615 == 6:315:36:315:3 == 2525

936936 == 9:936:99:936:9 == 1414

77887788 == 77:1188:1177:1188:11 == 7878

15851585 == 15:585:515:585:5 == 317317

16481648 == 16:1648:1616:1648:16 == 1313

21632163 == 21:2163:2121:2163:2 1 == 1313

3711137111 == 37:37111:3737:37111:37 == 1313

b)

666999666999