\(2\dfrac{3}{4}=\dfrac{2\times4+3}{4}=\dfrac{11}{4}\\ 3\dfrac{4}{5}=\dfrac{3\times5+4}{5}=\dfrac{19}{5}\\ 4\dfrac{3}{5}=\dfrac{4\times5+3}{5}=\dfrac{23}{5}\\ 11\dfrac{12}{13}=\dfrac{11\times13+12}{13}=\dfrac{155}{13}\\ 12\dfrac{11}{13}=\dfrac{12\times13+11}{13}=\dfrac{167}{13}\\ 3\dfrac{3}{5}=\dfrac{3\times5+3}{5}=\dfrac{18}{5}\)

2\(\dfrac{3}{4}\)=\(\dfrac{11}{4}\)

3\(\dfrac{4}{5}\)=\(\dfrac{19}{5}\)

4\(\dfrac{3}{5}\)=\(\dfrac{23}{5}\)

11\(\dfrac{12}{13}\)=\(\dfrac{155}{13}\)

12\(\dfrac{11}{13}\)=\(\dfrac{167}{13}\)

3\(\dfrac{3}{5}\)=\(\dfrac{18}{5}\).

của mình bị lỗi nha bạn

xl bạn

\(1\dfrac{1}{5}+1\dfrac{2}{4}=\dfrac{6}{5}+\dfrac{6}{4}=\dfrac{24}{20}+\dfrac{30}{20}=\dfrac{54}{40}\)

Cách chuyển hỗn số thành phân số :

\(1\dfrac{1}{5}=\dfrac{1x5+1}{5}=\dfrac{6}{5}\)

\(1\dfrac{2}{4}=\dfrac{1x4+2}{4}\dfrac{6}{4}\)

\(1\dfrac{1}{5}+1\dfrac{2}{4}=\dfrac{6}{5}+\dfrac{3}{2}=\dfrac{6\times2}{5\times2}+\dfrac{3\times5}{2\times5}=\dfrac{12}{10}+\dfrac{15}{10}=\dfrac{12+15}{10}=\dfrac{27}{10}.\)

4\(\dfrac{1}{2}\)=4,5      3\(\dfrac{4}{5}\)=3,8         2\(\dfrac{3}{4}\)=2,75      1\(\dfrac{12}{25}\)=1,48.

4 1/2=4,5

3 4/5=3,8

2 3/4=2,75

1 12/25=1,48

đúng 100% nha

\(4\dfrac{1}{2}\)=4\(\dfrac{5}{10}\)=4,5

\(3\dfrac{4}{5}\)=3\(\dfrac{8}{10}\)=3,8

\(2\dfrac{3}{4}\)=2\(\dfrac{75}{100}\)=2,75

1\(\dfrac{12}{25}\)=1\(\dfrac{48}{100}\)=1,48

\(2\dfrac{2}{3}=\dfrac{2\times3+2}{3}=\dfrac{8}{3}\)

\(3\dfrac{2}{1}=\dfrac{3\times1+2}{1}=\dfrac{5}{1}\)

\(\dfrac{8}{3}:\dfrac{5}{1}=\dfrac{8}{3}\times\dfrac{1}{5}=\dfrac{8}{15}\)

Chuyển hỗn số thành phân số :

\(2\dfrac{2}{3}=\dfrac{2x3+2}{3}=\dfrac{8}{3}\)

\(3\dfrac{2}{1}=\dfrac{3x1+2}{3}=\dfrac{5}{3}\)

Vậy nên :

\(2\dfrac{2}{3}:3\dfrac{2}{1}=\dfrac{8}{3}:\dfrac{5}{3}=\dfrac{8}{3}x\dfrac{3}{5}=\dfrac{24}{15}=\dfrac{8}{5}\)

\(3\dfrac{2}{1}=\dfrac{3x1+2}{1}=\dfrac{5}{1}\)

\(\dfrac{8}{3}x\dfrac{1}{5}=\dfrac{8}{15}\)

a) Các phân số đảo ngược là:

\(\dfrac{5}{8}\rightarrow\dfrac{8}{5};\dfrac{3}{4}\rightarrow\dfrac{4}{3};\dfrac{1}{2}\rightarrow\dfrac{2}{1}=2\)

b) \(\dfrac{3}{7}:\dfrac{5}{8}=\dfrac{3}{7}\times\dfrac{8}{5}=\dfrac{24}{35}\)

\(\dfrac{8}{7}:\dfrac{3}{4}=\dfrac{8}{7}\times\dfrac{4}{3}=\dfrac{32}{21}\)

\(\dfrac{1}{3}:\dfrac{1}{2}=\dfrac{1}{3}\times2=\dfrac{2\times1}{3}=\dfrac{2}{3}\)

\(\dfrac{54}{10}=5,4\)

\(4\dfrac{78}{1000}=4+\dfrac{78}{1000}=4+0,078=4,078\)

\(18\dfrac{4}{100}=18+\dfrac{4}{100}=18+0,04=18,04\)

\(\dfrac{1990}{10000}=\dfrac{199}{1000}=0,199\)

\(\dfrac{54}{10}=\dfrac{27}{5}=5,4\)

\(4\dfrac{78}{1000}=\dfrac{39}{125}=0,312\)

\(18\dfrac{4}{100}=\dfrac{18}{25}=0,72\)

\(\dfrac{1990}{10000}=\dfrac{199}{1000}=0,199\)

5410=5,41054​=5,4

4781000=4+781000=4+0,078=4,0784100078​=4+100078​=4+0,078=4,078

184100=18+4100=18+0,04=18,04181004​=18+1004​=18+0,04=18,04

199010000=1991000=0,199100001990​=1000199​=0,199

đây nè

a,A,C,D

b,C

a) Câu A;D

b) Câu C

a. A,D

b. C

\(\dfrac{23}{7}\)

23/7

23/7

3\(\dfrac{1}{5}\)=3+\(\dfrac{1}{5}\)=\(\dfrac{16}{5}\)

C

C

\(7\dfrac{4}{5}và9\dfrac{1}{2}\\ Tacó:7< 9\\ \Rightarrow7\dfrac{4}{5}< 9\dfrac{1}{2}\\ 7\dfrac{1}{6}và3\dfrac{4}{5}\\ Tacó:7>3\\ \Rightarrow7\dfrac{1}{6}>3\dfrac{4}{5}\)

Câu cuối không phải hỗn số