a, Ta có:

\(\left(5\frac{3}{7}+2\frac{4}{9}\right)-\left(1\frac{4}{9}+3\frac{3}{7}\right)\)\(=5\frac{3}{7}+2\frac{4}{9}-1\frac{4}{9}-3\frac{3}{7}\)\(=5\frac{3}{7}-3\frac{3}{7}+2\frac{4}{9}-1\frac{4}{9}\)

\(=2+1\)\(=3\)

b, Bạn làm tương tự nhé!!! bạn phá ngoặc ra rồi nhóm các số như mình làm ở trên nha!!!

a) \(\left(5\frac{3}{7}+2\frac{4}{9}\right)-\left(1\frac{4}{9}+\frac{3}{7}\right)\)

\(=5\frac{3}{7}+2\frac{4}{9}-1\frac{4}{9}-\frac{3}{7}\)

\(=\left(5\frac{3}{7}-\frac{3}{7}\right)+\left(1\frac{4}{9}-2\frac{4}{9}\right)\)

\(=5+\left(-1\right)\)

\(=4\)

b)\(\left(3\frac{4}{5}+5\frac{3}{4}\right)-\left(2\frac{3}{4}+1\frac{4}{5}\right)\)

\(=3\frac{4}{5}+5\frac{3}{4}-2\frac{3}{4}-1\frac{4}{5}\)

\(=\left(3\frac{4}{5}-1\frac{4}{5}\right)+\left(5\frac{3}{4}-2\frac{3}{4}\right)\)

\(=2+3=5\)

39/35

\(\frac{3}{5}\).\(\frac{-9}{13}\)+\(\frac{4}{13}\).\(\frac{-3}{5}\)+\(\frac{12}{7}\)=\(\frac{3}{5}\).\(\frac{-9}{13}\)+\(\frac{-4}{13}\).\(\frac{3}{5}\)+\(\frac{12}{7}\)

                                                                =\(\frac{3}{5}\).(\(\frac{-9}{13}\)+\(\frac{-4}{13}\))+\(\frac{12}{7}\)

                                                                =     \(\frac{3}{5}\).-1+\(\frac{12}{7}\)

                                                                =\(\frac{-3}{5}\)+\(\frac{12}{7}\)

                                                              =\(\frac{39}{35}\)

= ( 1 + 9  ) + ( 2 + 8 ) + ( 3 + 7 ) + ( 4 + 6 ) + 5

= 10 + 10 + 10 + 10 + 5

= 10 * 4 + 5

= 40 + 5 

= 45

= 45 nha bạn

Có 9 số hạng

Tổng=(1+9)x9:2=10x9:2=90:2=45

địt con mẹ mày lên

\(\dfrac{1}{3}\)-\(\dfrac{2}{15}\)+\(\dfrac{14}{15}\)=\(\dfrac{3}{15}\)-\(\dfrac{2}{15}\)+\(\dfrac{14}{15}\)

=\(\dfrac{13}{15}\)

\(\dfrac{3}{5}\)+4-\(\dfrac{6}{7}\)=\(\dfrac{3}{5}\)+\(\dfrac{20}{5}\)-\(\dfrac{6}{7}\)=\(\dfrac{23}{5}\)-\(\dfrac{6}{7}\)=\(\dfrac{161}{35}\)-\(\dfrac{30}{35}\)=\(\dfrac{131}{35}\)

A)2/3-(1/6+1/8)=2/3-7/24=3/8

B)5/7*14/11*5/7*2/11*5/11*5/7

=5/7*(14/11*2/11*5/11)

=5/7*140/1331=70/1331

C)4/7*(5/4-2/3)*7/8

=4/7*7/12*7/8=1/3*7/8=7/24

Đ)10/1*3+10/3*5+10/5*7+10/7*9+10/9*11

=30/1+50/3+70/5+90/7+110/9

=10+10+10+10+110/9 =40+110/9

=470/9

sao là nhân đúng ko vậy thì

a) 2/3-(1/6+1/8)

=2/3-14/48

=18/48

b)5/7.14/11.5/7.2/11.5/11.5/7

= [ 5/7.5/7.5/7] . [ 2/11.5/11.14/11]

= 125/343 . 140/1331

= 17500/456533     bạn chưa học lũy thừa đúng ko hả con này lấy cả tử cả mẫu nhân với lũy thừa là xong cực nhanh đó

c) 4/7.(5/4-2/3).7/8

=4/7.10/12.7/8

=40/84.7/8

=280/672

d)10/1.3+10/3.5+10/5.7+10/7.9+10/9.11

= 30/1+50/3+70/5+90/7+110/9

=27010/315

A)2/3 - ( 1/6 + 1/8 )

= 2/3 - 7/24

= 3/8

B) 5/7 X 14/11 X 5/7 X 2/11 X 5/11 X 5/7

= 5/7 x ( 14/11 x 2/11 x 5/11 )

= 5/7 x 140/1331

= 100/13331

Đề yêu cầu gì vậy em?

đây là so sánh hay quy đồng v 

\(\dfrac{3}{5}v\text{à}\dfrac{7}{3}\\ MSC:15\\ \dfrac{3}{5}=\dfrac{3\times3}{5\times3}=\dfrac{9}{15};\dfrac{7}{3}=\dfrac{7\times5}{5\times3}=\dfrac{35}{15}\\ 9< 35\\ \Rightarrow\dfrac{3}{5}< \dfrac{7}{5}\\ \dfrac{9}{10}v\text{à}\dfrac{5}{4}\\MSC:20\\ \dfrac{9\times2}{10\times2}=\dfrac{18}{20};\dfrac{5}{4}=\dfrac{5\times5}{4\times5}=\dfrac{25}{20}\\ 18< 25\\ \Rightarrow\dfrac{9}{10}< \dfrac{5}{4}\\ \dfrac{2}{7}v\text{à}\dfrac{5}{4}\\ MSC:28\\ \dfrac{2}{7}=\dfrac{2\times4}{7\times4}=\dfrac{8}{28};\dfrac{5}{4}=\dfrac{5\times7}{4\times7}=\dfrac{35}{28}\\ 8< 35\\ \dfrac{2}{7}< \dfrac{5}{4}\\ \dfrac{8}{9}v\text{à}\dfrac{11}{6}\\ MSC:18\\ \dfrac{8\times2}{9\times2}=\dfrac{16}{18};\dfrac{11}{6}=\dfrac{11\times3}{6\times3}=\dfrac{33}{18}\\ 16< 33\\ \Rightarrow\dfrac{8}{9}< \dfrac{11}{6}\)

Quy đồng hả ?

\(\dfrac{3}{5}và\dfrac{7}{3}=\dfrac{3}{5}=\dfrac{3\times3}{5\times3}=\dfrac{9}{15};\dfrac{7}{3}=\dfrac{7\times5}{3\times5}=\dfrac{35}{15}\)

\(\dfrac{9}{10}và\dfrac{5}{4}=\dfrac{9}{10}=\dfrac{9\times2}{10\times2}=\dfrac{18}{20};\dfrac{5}{4}=\dfrac{5\times5}{4\times5}=\dfrac{25}{20}\)

\(\dfrac{2}{7}và\dfrac{5}{4}=\dfrac{2}{7}=\dfrac{2\times4}{7\times4}=\dfrac{8}{28};\dfrac{5}{4}=\dfrac{5\times7}{4\times7}=\dfrac{35}{28}\)

\(\dfrac{8}{9}và\dfrac{11}{6}=\dfrac{8}{9}=\dfrac{8\times2}{9\times2}=\dfrac{16}{18};\dfrac{11}{6}=\dfrac{11\times3}{6\times3}=\dfrac{33}{18}\)

\(\dfrac{6}{5}và\dfrac{13}{8}=\dfrac{6\times8}{5\times8}=\dfrac{48}{40};\dfrac{13}{8}=\dfrac{13\times5}{8\times5}=\dfrac{65}{40}\)

\(\dfrac{4}{5}và\dfrac{3}{2}=\dfrac{4}{5}=\dfrac{4\times2}{5\times2}=\dfrac{8}{10};\dfrac{3}{2}=\dfrac{3\times5}{2\times5}=\dfrac{15}{10}\)

\(\dfrac{5}{12}và\dfrac{7}{8}=\dfrac{5}{12}=\dfrac{5\times2}{12\times2}=\dfrac{10}{24};\dfrac{7}{8}=\dfrac{7\times3}{8\times3}=\dfrac{21}{24}\)

\(\dfrac{11}{4}và\dfrac{13}{6}=\dfrac{11}{4}=\dfrac{11\times3}{4\times3}=\dfrac{33}{12};\dfrac{13}{6}=\dfrac{13\times2}{6\times2}=\dfrac{26}{12}\)

3/5 + 2/3 + 4/5

=19/15 + 4/5

=31/15

4/9 - 3/14 : 4/7

=4/9 - 3/8

=5/72

Nhớ tích mk nhé !

\(\frac{3}{5}+\frac{2}{3}+\frac{4}{5}=\left(\frac{3}{5}+\frac{4}{5}\right)+\frac{2}{3}\)

=\(\frac{7}{5}+\frac{2}{3}=\frac{21}{15}+\frac{10}{15}=\frac{31}{15}\)

\(\frac{4}{9}-\frac{3}{14}:\frac{4}{7}=\frac{4}{9}-\frac{3}{14}.\frac{7}{4}\)

=\(\frac{4}{9}-\frac{3}{8}=\frac{32}{72}-\frac{27}{72}=\frac{5}{72}\)

3/5+2/3+4/5=(3/5+4/5)+2/3

                 =7/5+2/3

                 =31/15

4/9-3/14:4/7=4/9-21/56

                 =35/504