Tính

          \(\frac{15}{25}+\frac{80}{125}+\frac{12}{42}+\frac{78}{100}+\frac{18}{12}\)

          \(\frac{3}{5}+\frac{16}{25}+\frac{6}{21}+\frac{39}{50}+\frac{3}{2}\)

          \(\frac{15}{25}+\frac{16}{25}+\frac{39}{50}+\frac{6}{21}+\frac{3}{2}\)

           \(\frac{62}{50}+\frac{39}{50}+\frac{12}{42}+\frac{63}{42}\)

           \(\frac{101}{50}+\frac{75}{42}\)

           \(\frac{4242}{2100}+\frac{3750}{2100}\)

          \(\frac{7992}{2100}\)

54/12:64/12=27/32

56/45x54/51=112/85

56/20+58/21=584/105

21/78-12/78=3/26

a).27/32

b).336/305

c).584/105

d).3/26

\(\frac{3}{5}+\frac{2}{7}=\frac{21}{35}+\frac{10}{35}=\frac{31}{35}\)

\(\frac{3}{9}-\frac{1}{5}=\frac{15}{45}-\frac{9}{45}=\frac{6}{45}\)

\(\frac{2}{5}\times\frac{3}{7}=\frac{6}{35}\)

\(\frac{4}{9}:\frac{2}{5}=\frac{4}{9}\times\frac{5}{2}=\frac{20}{18}\)

Trả lời 

\(\frac{3}{5}+\frac{2}{7}=\frac{21}{35}+\frac{10}{35}=\frac{31}{35}\)

\(\frac{3}{9}-\frac{1}{5}=\frac{15}{45}-\frac{9}{45}=\frac{6}{45}=\frac{2}{15}\)

\(\frac{2}{5}\times\frac{3}{7}=\frac{6}{35}\)

\(\frac{4}{9}:\frac{2}{5}=\frac{4}{9}\times\frac{5}{2}=\frac{20}{18}=\frac{10}{9}\)

Study well 

a) \(\frac{3}{5}\times y+\frac{1}{2}:\frac{5}{3}-\frac{5}{4}=\frac{1}{2}\times\frac{1}{3}\)

\(\Rightarrow\frac{3}{5}\times y+\frac{3}{10}-\frac{5}{4}=\frac{1}{6}\)

\(\Rightarrow\frac{3}{5}\times y+\left(-\frac{19}{20}\right)=\frac{1}{6}\)

\(\Rightarrow\frac{3}{5}\times y=\frac{67}{60}\)

\(\Rightarrow y=\frac{67}{36}\)

b) \(\frac{4}{5}:y+\frac{1}{4}\times\frac{1}{6}-\frac{1}{2}=\frac{1}{3}\times\frac{5}{2}\)

\(\Rightarrow\frac{4}{5}:y+\frac{1}{24}-\frac{1}{2}=\frac{5}{6}\)

\(\Rightarrow\frac{4}{5}:y+\left(-\frac{11}{24}\right)=\frac{5}{6}\)

\(\Rightarrow\frac{4}{5}:y=\frac{5}{6}+\frac{11}{24}=\frac{31}{24}\)

\(\Rightarrow y=\frac{4}{5}:\frac{31}{24}=\frac{96}{155}\)

c) \(\frac{3}{5}\times y-\frac{4}{5}:3+\frac{1}{12}=\frac{3}{2}+\frac{1}{5}\)

\(\Rightarrow\frac{3}{5}\times y-\frac{4}{15}+\frac{1}{12}=\frac{17}{10}\)

\(\Rightarrow\frac{3}{5}\times y-\frac{4}{15}=\frac{97}{60}\)

\(\Rightarrow\frac{3}{5}\times y=\frac{113}{60}\)

\(\Rightarrow y=\frac{113}{36}\)

4 x 4 = 16

4 x 1 = 4

4 x 5 = 20

4 x 8 = 32

4 x 9 = 36

9 x 9 = 81 

4 x 4 = 16

4 x 1 = 4

4 x 5 = 20

4 x 8 = 32

4 x 9 = 36

9 x 9 = 81

Chúc bạn học tốt !!!

@nguyễn thị phương anh đây nhé :

\(\frac{12}{21}+\frac{11}{22}=\frac{264}{462}+\frac{231}{462}=\frac{495}{462}\)

\(\frac{9}{32}+\frac{35}{11}=\frac{99}{352}+\frac{1120}{352}=\frac{1219}{352}\)

\(\frac{12}{21}+\frac{11}{22}=\frac{4}{7}+\frac{1}{2}=\frac{8}{14}+\frac{7}{14}=\frac{15}{14}\)

\(\frac{9}{32}+\frac{35}{11}=\frac{99}{352}+\frac{1120}{352}=\frac{1219}{352}\)

mình gọi phép tính trên là Acho đỡ rối nha

có A=1-1/2+1/2-1/4+1/4-1/8+1/8-1/16+1/16-1/32

A=1-1/32

A=31/32

Ta có:

1/2+1/4+1/8+1/16+1/32

=16/32+8/32+4/32+2/32+1/32

=31/32

tớ đang bị kẹt ở phân số \(\frac{1357}{4770}\)

\(a.\frac{3}{5}+\frac{9}{8}\)

\(=\frac{24}{40}+\frac{45}{40}\)

\(=\frac{24+45}{40}\)

\(=\frac{69}{40}\)

\(b.\frac{7}{3}-\frac{5}{6}\)

\(=\frac{14}{6}-\frac{5}{6}\)

\(=\frac{14-5}{6}\)

\(=\frac{9}{6}=\frac{3}{2}\)

câu 1 : mẫu số chung là 12

nhưng mik lại chả thấy cái nào phù hợp 

mình xin lỗi còn câu D là  số 12 đó !