^{_{\(\dfrac{5}{7}=\dfrac{15}{21};\dfrac{6}{8}=\dfrac{3}{4};\dfrac{8}{9}=\dfrac{16}{18};\dfrac{12}{16}=\dfrac{18}{24}\)}}

\(\dfrac{5}{7}=\dfrac{15}{21};\dfrac{6}{8}=\dfrac{18}{24};\dfrac{8}{9}=\dfrac{16}{18};\dfrac{3}{4}=\dfrac{12}{16}\)

5/7=15/21;6/8=3/4;8/9=16/18;12/16=18/24

21/49=3/7

36/98=18/49

18/34=9/17

k cho mik nha!

3/7=21/49

tk cho mình

Ta có:3/7=3/7;9/17=9/17;21/49=3/7;18/34=9/17;36/98=18/49

Vậy các phân số = nhau là:3/7 và 3/7hay 3/7 và 21/49

              Đáp số :3/7=21/49

  3\7 = 21\49

  9\17 = 18\34

18\49 = 36\98

Vì:

\(\dfrac{12}{20}=\dfrac{12:4}{20:4}=\dfrac{3}{5}\)

\(\dfrac{12}{14}=\dfrac{12:2}{14:2}=\dfrac{6}{7}\)

\(\dfrac{18}{21}=\dfrac{18:3}{21:3}=\dfrac{6}{7}\)

\(\dfrac{60}{100}=\dfrac{60:20}{100:20}=\dfrac{3}{5}\)

Vậy \(\dfrac{3}{5}=\dfrac{12}{20}=\dfrac{60}{100}\)            ;                 \(\dfrac{6}{7}=\dfrac{12}{14}=\dfrac{18}{21}\)

\(#Wendy.Dang\)

4/7 - 12/21

15/8 - 45/24

8/9 - 16/18

20/28 - 5/7

\(\dfrac{4}{7}=\dfrac{12}{21};\dfrac{15}{8}=\dfrac{45}{24};\dfrac{8}{9}=\dfrac{16}{18};\dfrac{5}{7}=\dfrac{20}{28}\)

4/7 - 12/21

15/8 - 45/24 

8/9 - 16/18

20/28 - 5/7 

\(\dfrac{20}{35}\text{=}\dfrac{4}{7}\)

\(\dfrac{5}{15}\text{=}\dfrac{1}{3}\)

\(\dfrac{12}{21}\text{=}\dfrac{4}{7}\)

\(\dfrac{8}{10}\text{=}\dfrac{4}{5}\)

\(\dfrac{20}{30}\text{=}\dfrac{2}{3}\)

\(\Rightarrow\left(\dfrac{20}{35}\text{=}\dfrac{12}{21}\text{=}\dfrac{4}{7}\right);\left(\dfrac{20}{30}\text{=}\dfrac{2}{3}\right).\)

4/7 = 12/21 = 20/35

HT

20/35=12/21=4/7
2/3=20/30