24 : 8 = 3

16 : 8 = 2

56 : 8 = 7

80 : 8 = 10

40 : 8 = 5

48 : 8 = 6

64 : 8 = 8

48 : 6 = 8

32 : 8 = 4

8 : 8 = 1

72 : 8 = 9

56 : 7 = 8

24 : 8 =3 

16 : 8 = 2 

56 : 8 = 7 

80 : 8 = 10

40 : 8 = 5

48 : 8 = 6 

64 : 8 = 8 

48 : 6 = 8

32 : 8 = 4

8 : 8 = 1

72 : 8 = 9 

56 : 7 = 8

=3

=2

=7

=10

=5

=6

=8

=8

=4

=1

=9

=8

a)\(8-\frac{3}{5}=\frac{40}{5}-\frac{3}{5}=\frac{37}{5}\)

b)\(\frac{24}{15}\times\frac{56}{72}\times\frac{10}{14}=\frac{13440}{15120}=\frac{8}{9}\)

c)\(\frac{32}{48}\times\frac{35}{21}\times\frac{63}{14}\times\frac{9}{30}=\frac{2}{3}\times\frac{5}{3}\times\frac{9}{2}\times\frac{3}{10}=\frac{270}{180}=\frac{3}{2}\)

d)\(7-\frac{72}{48}\times\frac{56}{60}-3=7-\frac{3}{2}\times\frac{14}{15}-3\)

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

\(=\frac{35}{5}-\frac{7}{5}-\frac{15}{5}\)

\(=\frac{13}{5}\)

#H

(Sai thì sửa)

8 + 8 = 16        32 + 8 = 40       56 + 8 = 64

16 + 8 = 24       40 + 8 = 48       64 + 8 = 72

24 + 8 = 32        48 + 8 = 56       72 + 8 = 80

\(\frac{1}{2}+\frac{5}{6}+\frac{11}{12}+\frac{19}{20}+...+\frac{89}{90}\)

\(=1-\frac{1}{2}+1-\frac{1}{6}+1-\frac{1}{12}+1-\frac{1}{20}+...+1-\frac{1}{90}\)

\(=9-\left(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{90}\right)\)

\(=9-\left(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{9.10}\right)\)

\(=9-\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+....+\frac{1}{9}-\frac{1}{10}\right)\)

\(=9-\left(1-\frac{1}{10}\right)\)

\(=9-\frac{9}{10}=\frac{81}{10}\)

16 : 8 = 2    32 : 8 = 4    80 : 8 = 10    48 : 8 = 6

24 : 8 = 3    56 : 8 = 7    40 : 8 = 5    8 : 8 = 1

64 : 8 = 8    72 : 8 = 9

rút gọn thành

1/2 x 2/3 x 3/4 x 4/5 x 5/6 x 6/7 x 7/8 x 8/9

1x2x3x4x5x6x7x8

__________________

2x3x4x5x6x7x8x9

gạch các số giống nhau ở tử và mẫu và bằng 1/9

Câu 1: \(\frac{17}{51}\)x \(\frac{45}{30}\)= \(\frac{1}{3}\)x \(\frac{3}{2}\)

                                   = \(\frac{1}{2}\).

Câu 2: \(\frac{24}{15}\)x \(\frac{56}{72}\)x \(\frac{10}{14}\)= \(\frac{8}{5}\)x \(\frac{7}{9}\)x \(\frac{5}{7}\)

                                                 = \(\frac{56}{45}\)x \(\frac{5}{7}\)

                                                 = \(\frac{8}{9}\)

Câu 3: \(\frac{32}{48}\times\frac{35}{21}\times\frac{63}{14}\times\frac{9}{30}=\frac{2}{3}\times\frac{5}{3}\times\frac{9}{2}\times\frac{3}{10}=\frac{3}{2}\)

k nha

a)17/51x45/40=1/3x3/2=3/6=1/2

b)24/15x56/72x10/14=8/5x7/9x5/7=8/9

c)32/48x35/21x63/14x9/30=2/3x5/3x9/2x3/10=3/2

x x 134 -x x24 -x x 10 = x x ( 134 - 24 - 10)

x = x x 100

x = 1300 : 100

x = 13

300

300

= 300