\(\dfrac{3}{15}-\dfrac{5}{35}=\dfrac{1}{5}-\dfrac{1}{7}=\dfrac{7}{35}-\dfrac{5}{35}=\dfrac{2}{35}\)

1/5-1/7= 7/35-5/35=2/35

3/15 - 5/35 = 1/5 - 1/7 = 7/35 - 5/35 = 2/35

3/15 - 5/35 

= 1/5 - 1/7

= 2/35

3/15-5/35=1/5-5/35=7/35-5/35=2/35

\(\frac{3}{15}-\frac{5}{35}=\frac{1}{5}-\frac{1}{7}=\frac{7}{35}-\frac{5}{35}=\frac{2}{35}\)

3/15 - 5/35

= 1/5 - 1/7

= 2/35

\(\frac{3}{15}\)-\(\frac{5}{35}\)=\(\frac{1}{5}\)-\(\frac{1}{7}\)

\(\frac{1}{5}\)- \(\frac{1}{7}\) = \(\frac{7}{35}\)- \(\frac{5}{35}\)= \(\frac{7-5}{35}\)=\(\frac{2}{35}\)

tick nhé

Hướng dẫn giải:

a: =1/5-1/7=2/35

c: =3/5-1/7=21/35-5/35=16/35

Ta có: \(\dfrac{21}{35}\)=\(\dfrac{21:7}{35:7}\)=\(\dfrac{3}{5}\)

Vậy \(\dfrac{3}{5}\)+\(\dfrac{5}{4}\)=\(\dfrac{12}{20}\)+\(\dfrac{25}{20}\)=\(\dfrac{37}{20}\)

\(\dfrac{9}{27}\)=\(\dfrac{9:9}{27:9}\)=\(\dfrac{1}{3}\) ; \(\dfrac{15}{20}\)=\(\dfrac{15:5}{20:5}\)=\(\dfrac{3}{4}\)

Vậy \(\dfrac{1}{3}\)+\(\dfrac{3}{4}\)=\(\dfrac{4}{12}\)+\(\dfrac{9}{12}\)=\(\dfrac{13}{12}\)

=4/5+1/5=1

\(\dfrac{4}{5}+\dfrac{3}{15}=\dfrac{4}{5}+\dfrac{3:3}{15:3}=\dfrac{4}{5}+\dfrac{1}{5}=\dfrac{5}{5}=1\)

bằng 1

HT

`3/15 + 5/25`

`= 1/5 + 1/5`

`=(1+1)/5`

`=2/5`

`3/15+5/25`

`=(3:3)/(15:3)+(5:5)/(25:5)`

`=1/5+1/5`

`=2/5`

`#``\text{Lócc}`

\(\dfrac{15}{35}+\dfrac{7}{10}=\dfrac{3}{7}+\dfrac{7}{10}=\dfrac{30}{70}+\dfrac{49}{70}=\dfrac{79}{70}\)

\(\dfrac{27}{72}+\dfrac{11}{24}=\dfrac{3}{8}+\dfrac{11}{24}=\dfrac{9}{24}+\dfrac{11}{24}=\dfrac{20}{24}=\dfrac{5}{6}\)

\(\dfrac{6}{12}+\dfrac{7}{6}=\dfrac{1}{2}+\dfrac{7}{6}=\dfrac{3}{6}+\dfrac{7}{6}=\dfrac{10}{6}=\dfrac{5}{3}\)