\(a,\dfrac{8}{24}-\dfrac{5}{25}=\dfrac{1}{3}-\dfrac{1}{5}=\dfrac{5}{15}-\dfrac{3}{15}=\dfrac{2}{15}\)

\(b,\dfrac{18}{21}-\dfrac{12}{27}=\dfrac{6}{7}-\dfrac{4}{9}=\dfrac{26}{63}\)

a) \(\dfrac{8}{24}-\dfrac{5}{25}=\dfrac{8:8}{24:8}-\dfrac{5:5}{25:5}=\dfrac{1}{3}-\dfrac{1}{5}=\dfrac{5}{15}-\dfrac{3}{15}=\dfrac{2}{15}\)

b) \(\dfrac{18}{21}-\dfrac{12}{27}=\dfrac{18:3}{21:3}-\dfrac{12:3}{27:3}=\dfrac{6}{7}-\dfrac{4}{9}=\dfrac{54}{63}-\dfrac{28}{63}=\dfrac{26}{63}\)

giúp mình với mọi người ơi

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

\(\dfrac{6}{7}-\dfrac{4}{9}=\dfrac{54}{63}-\dfrac{28}{63}=\dfrac{26}{63}\)

A) \(\frac{7}{8}-\frac{5}{12}=\frac{84}{96}-\frac{40}{96}=\frac{44}{96}=\frac{11}{24}\)

B)\(\frac{8}{15}-\frac{2}{5}=\frac{8}{15}-\frac{6}{15}=\frac{2}{15}\)

C)\(\frac{5}{6}-\frac{3}{10}=\frac{50}{60}-\frac{18}{60}=\frac{32}{60}=\frac{8}{15}\)

D)\(\frac{7}{10}-\frac{1}{5}=\frac{7}{10}-\frac{2}{10}=\frac{5}{10}=\frac{1}{2}\)

2)A)\(\frac{5}{10}-\frac{2}{15}=\frac{1}{2}-\frac{2}{15}=\frac{15}{30}-\frac{4}{30}=\frac{11}{30}\)

B)\(\frac{5}{20}-\frac{1}{6}=\frac{1}{4}-\frac{1}{6}=\frac{6}{24}-\frac{4}{24}=\frac{2}{24}=\frac{1}{12}\)

C)\(\frac{6}{18}-\frac{6}{24}=\frac{1}{3}-\frac{1}{4}=\frac{4}{12}-\frac{3}{12}=\frac{1}{12}\)

D)\(\frac{5}{9}-\frac{3}{12}=\frac{5}{9}-\frac{1}{4}=\frac{20}{36}-\frac{9}{36}=\frac{11}{36}\)

Chúc bạn học tốt

b: 12/20+6/18=3/5+1/3=9/15+5/15=14/15

c: 8/12+20/30=2/3+2/3=4/3

d: 10/12+12/36=5/6+2/6=7/6

a)8/5-18/27=216/135-90/135=126/135

b)3/5-1/3=9/15-5/15=4/15(rút gọn p/s)

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

d)6/7-12/27=162/189-84/189=78/189

Nay rảnh lại qua làm mấy bài lớp 4 ^^

Tui làm luôn kh ghi đề nhá

1, 

\(\frac{2}{3}+\frac{8}{15}=\frac{6}{5}\)

\(\frac{2}{5}+\frac{2}{3}=\frac{16}{15}\)

\(\frac{2}{3}+\frac{5}{6}=\frac{3}{2}\)

2, 

\(\cdot\frac{3}{7}+\frac{6}{5}+\frac{4}{7}\)

\(=\frac{3}{7}+\frac{4}{7}+\frac{6}{5}\)

\(=1+\frac{6}{5}\)

\(=\frac{11}{5}\)

\(\cdot\frac{6}{4}+\frac{7}{3}+\frac{4}{4}+\frac{3}{3}\)

\(=\frac{6}{4}+\frac{4}{4}+\frac{7}{3}+\frac{3}{3}\)

\(=\frac{10}{4}+\frac{10}{3}\)

\(=\frac{35}{6}\)

2, 

a: =8/5-2/3=24/15-10/15=14/15

12/20-6/18=3/5-1/3=9/15-5/15=4/15

b: 18/21-12/27=6/7-7/9=54/63-49/63=5/63

8/12-20/50=2/3-2/5=10/15-6/15=4/15

\(a,\dfrac{8}{5}-\dfrac{18}{27}=\dfrac{8}{5}-\dfrac{2}{3}=\dfrac{14}{15}\\ \dfrac{12}{20}-\dfrac{6}{18}=\dfrac{3}{5}-\dfrac{1}{3}=\dfrac{4}{15}\\ b,\dfrac{18}{21}-\dfrac{12}{27}=\dfrac{6}{7}-\dfrac{4}{9}=\dfrac{26}{63}\\ \dfrac{8}{12}-\dfrac{20}{50}=\dfrac{2}{3}-\dfrac{2}{5}=\dfrac{4}{15}\)

1, Rút gọn rồi tính 

a) \(\frac{4}{5}+\frac{3}{15}\)

= \(\frac{4}{5}+\frac{1}{5}\)

= \(\frac{5}{5}\)

= \(1\)

b) \(\frac{2}{3}+\frac{32}{24}\)

= \(\frac{2}{3}+\frac{4}{3}\)

= \(\frac{6}{3}\)

= \(2\)

c) \(\frac{5}{6}+\frac{15}{18}\)

= \(\frac{5}{6}+\frac{5}{6}\)

= \(\frac{10}{6}\)

= \(\frac{5}{3}\)

2, Tính rồi rút gọn 

a) \(\frac{8}{15}+\frac{2}{3}\)

= \(\frac{8}{15}+\frac{10}{15}\)

= \(\frac{18}{15}\)

= \(\frac{6}{5}\)

b) \(\frac{3}{7}+\frac{4}{8}\)

= \(\frac{24}{56}+\frac{28}{56}\)

= \(\frac{52}{56}\)

= \(\frac{13}{14}\)

Đáp án:

a) 1

b) 2

c) 5/3

Bài 3.Tính rồi rút gọn

a)6/5

b) 13/14