bài 4:so sánh

5/2 lớn hơn 3/7

4/3 lớn hơn,3/2 lớn hơn 

bài 6:rút gọn các phân số sau:

3/9=1/3      9/12=3/4          8/18=4/9         60/36=10/6         17/34=1/2              17/51=1/3           35/100=7/20           25/100=1/4                  8/1000=1/125                 24/30=4/5           18/54=1/3           72/42=12/7

đay nhé mk chưa làm hết đc bn viết liền quá mk nhìn khó mà mk hỏi bài 7 là nhân hay cộng vậy?

4 phần 5 trừ 11 phần 5 =

1 + 1 = 2

2 + 2 = 4

3 + 3 = 6

4 + 4 = 8

5 + 5 = 10

\(a,=\frac{7-1}{1.3.7}+\frac{9-3}{3.7.9}+\frac{13-7}{7.9.13}+\frac{15-9}{9.13.15}\)\(+\frac{19-13}{13.15.19}\)

\(=\frac{1}{1.3}-\frac{1}{3.7}+\frac{1}{3.7}-\frac{1}{7.9}+\frac{1}{7.9}-\frac{1}{9.13}+\frac{1}{9.13}-\frac{1}{13.15}+\frac{1}{13.15}-\frac{1}{15.19}\)

\(=\frac{1}{1.3}-\frac{1}{15.19}=\frac{95}{285}-\frac{1}{285}=\frac{94}{285}\)

\(b,=\frac{1}{6}.\left(\frac{6}{1.3.7}+\frac{6}{3.7.9}+\frac{6}{7.9.13}+\frac{6}{9.13.15}+\frac{6}{13.15.19}\right)\)

làm giống như trên

\(c,=\frac{1}{8}.\left(\frac{1}{1.2.3}+\frac{1}{2.3.4}+\frac{1}{3.4.5}+...+\frac{1}{48.49.50}\right)\)

\(=\frac{1}{16}.\left(\frac{2}{1.2.3}+\frac{2}{2.3.4}+\frac{2}{3.4.5}+...+\frac{2}{48.49.50}\right)\)

\(=\frac{1}{16}.\left(\frac{3-1}{1.2.3}+\frac{4-2}{2.3.4}+\frac{5-3}{3.4.5}+...+\frac{50-48}{48.49.50}\right)\)

\(=\frac{1}{16}.\left(\frac{1}{1.2}-\frac{1}{2.3}+\frac{1}{2.3}-\frac{1}{3.4}+\frac{1}{3.4}-\frac{1}{4.5}+...+\frac{1}{48.49}-\frac{1}{49.50}\right)\)

\(=\frac{1}{16}.\left(\frac{1}{2}-\frac{1}{2450}\right)=\frac{1}{16}.\left(\frac{1225}{2450}-\frac{1}{2450}\right)=\frac{153}{4900}\)

\(d,=\frac{5}{7}.\left(\frac{7}{1.5.8}+\frac{7}{5.8.12}+\frac{7}{8.12.15}+...+\frac{7}{33.36.40}\right)\)

\(=\frac{5}{7}.\left(\frac{8-1}{1.5.8}+\frac{12-5}{5.8.12}+\frac{15-8}{8.12.15}+...+\frac{40-33}{33.36.40}\right)\)

\(=\frac{5}{7}.\left(\frac{1}{1.5}-\frac{1}{5.8}+\frac{1}{5.8}-\frac{1}{8.12}+\frac{1}{8.12}-\frac{1}{12.15}+...+\frac{1}{33.36}-\frac{1}{36.40}\right)\)

\(=\frac{5}{7}.\left(\frac{1}{5}-\frac{1}{1440}\right)=\frac{5}{7}.\left(\frac{288}{1440}-\frac{1}{1440}\right)=\frac{41}{288}\)

P/S: . là nhân nha

sxasxsxxsxsxssxsxsxsxsx232332321322

Cái này dễ thế mà ko bít lm

1/2 ; 2/3 ; 7/8 ; 9/10 ; 6/5

a; 5\(\dfrac{3}{4}\) : 3 + 2\(\dfrac{1}{4}\).\(\dfrac{1}{3}\) - \(\dfrac{3}{8}\)

= \(\dfrac{23}{4}\) : 3 + \(\dfrac{9}{4}\).\(\dfrac{1}{3}\) - \(\dfrac{3}{8}\)

= \(\dfrac{23}{4}\) x \(\dfrac{1}{3}\) + \(\dfrac{3}{4}\) - \(\dfrac{3}{8}\)

= \(\dfrac{23}{12}\) + \(\dfrac{3}{4}\) - \(\dfrac{3}{8}\)

= \(\dfrac{46}{24}\) + \(\dfrac{18}{24}\) - \(\dfrac{9}{24}\)

= \(\dfrac{64}{24}\) - \(\dfrac{9}{24}\)

= \(\dfrac{55}{24}\)

sử dung kết hop

a, 23/4 : 3 + 9/4 x 1/3 - 3/8

=  7,8 + 12,22 - 3,8

= 20,02 - 3,8

  =16,22

b, 3/5 : 5/6 : 6/7 : 7/8 + 2/5 +23/35 

=3/5 x 6/5 x 7/6 x 8/7 + 2/5 + 23/35

a, 23/4 : 3 + 9/4 x 1/3 - 3/8= 7,8 + 12,22 - 3,8= 20,02 - 3,8 =16,22b, 3/5 : 5/6 : 6/7 : 7/8 + 2/5 +23/35 =3/5 x 6/5 x 7/6 x 8/7 + 2/5 + 23/35=24/25 + 2/5 + 23/35=1/5 x(24/5 + 2 +23/7)=1/5 x 353/35=353/175

Bài 7:

Số phần kẹo Hùng đã cho Hà và Hồng là:

\(\dfrac{2}{7}+\dfrac{1}{7}=\dfrac{3}{7}\left(phần\right)\)

Hùng còn lại số phần của gói kẹo là:

\(\dfrac{6}{7}-\dfrac{3}{7}=\dfrac{3}{7}\left(phần\right)\)

1:

 2 3/4

5 6/5

3 3/9

7 6/8

2:

1/3 + 2/3 + (3/4 + 1/4) = 2

=2

= 4 5/10

1:

\(2+\dfrac{3}{4}=\dfrac{8}{4}+\dfrac{3}{4}=\dfrac{11}{4};5+\dfrac{6}{5}=\dfrac{25}{5}+\dfrac{6}{5}=\dfrac{31}{5};\dfrac{3}{9}+3=\dfrac{1}{3}+\dfrac{9}{3}=\dfrac{10}{3}\)

2: 

a: \(=\left(\dfrac{1}{3}+\dfrac{2}{3}\right)+\left(\dfrac{3}{4}+\dfrac{1}{4}\right)\\ =1+1=2\)

b: \(=\left(\dfrac{3}{4}+\dfrac{2}{8}\right)+\left(\dfrac{3}{5}+\dfrac{4}{10}\right)\\ =\left(\dfrac{6}{8}+\dfrac{2}{8}\right)+\left(\dfrac{6}{10}+\dfrac{4}{10}\right)\\ =1+1=2\)

c:\(=\left(\dfrac{1}{10}+\dfrac{9}{10}\right)+\left(\dfrac{2}{10}+\dfrac{8}{10}\right)+\left(\dfrac{3}{10}+\dfrac{7}{10}\right)+\left(\dfrac{4}{10}+\dfrac{6}{10}\right)+\dfrac{5}{10}\\ =1+1+1+1+\dfrac{5}{10}=4\dfrac{5}{10}\)

a) Vì 4 < 5 nên \(\frac{3}{4}>\frac{3}{5}\)

b) Vì 4 < 5 nên \(\frac{4}{7}< \frac{5}{7}\)

c) Ta có :

\(\frac{2}{7}=\frac{2\times5}{7\times5}=\frac{10}{35}\)

\(\frac{4}{5}=\frac{4\times7}{5\times7}=\frac{28}{35}\)

Vì 10 < 28 nên \(\frac{10}{35}< \frac{28}{35}\)hay \(\frac{2}{7}< \frac{4}{5}\)

d) Ta có :

\(\frac{8}{9}=\frac{8\times10}{9\times10}=\frac{80}{90}\)

\(\frac{9}{10}=\frac{9\times9}{10\times9}=\frac{81}{90}\)

Vì 80 < 81 nên \(\frac{80}{90}< \frac{81}{90}\)hay \(\frac{8}{9}< \frac{9}{10}\)

e) Ta có :

\(\frac{10}{9}=\frac{10\times2}{9\times2}=\frac{20}{18}\)

Vì 19 < 20 nên \(\frac{19}{18}< \frac{20}{18}\)hay \(\frac{19}{18}< \frac{10}{9}\)

f) Ta có :

\(\frac{8}{3}=\frac{8\times4}{3\times4}=\frac{32}{12}\)

\(\frac{5}{6}=\frac{5\times2}{6\times2}=\frac{10}{12}\)

Vì 32 > 10 nên \(\frac{32}{12}>\frac{10}{12}\)hay \(\frac{8}{3}>\frac{5}{6}\)

bn nào dài được đầu tiên mà đúng mik sẽ k cho bn đó nhé

\(\frac{3}{4}>\frac{3}{5}\)

\(\frac{4}{7}< \frac{5}{7}\)

\(\frac{2}{7}< \frac{4}{5}\)

\(\frac{8}{9}< \frac{9}{10}\)

\(\frac{19}{18}< \frac{10}{9}\)

\(\frac{8}{3}>\frac{5}{6}\)