\(\frac{\text{30.25.7.8}}{\text{75.8.12.14}}=\frac{\left(30:6\right).\left(25:25\right).\left(7:7\right).\left(8:8\right)}{\left(75:25\right).\left(8:8\right).\left(12:6\right).\left(14:7\right)}=\frac{5..1.1.1}{3.1.2.2}=\frac{5}{12}\)

= 6.7.4.4.3.3.2.5.11

11.2.4.5.3.6.16.2.7.2.3,2

= 1

16

S=\(\frac{1}{5.6}+\frac{1}{6.7}+\frac{1}{7.8}+...+\frac{1}{24.25}\)

  = \(\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}+...+\frac{1}{24}-\frac{1}{25}\)

= \(\frac{1}{5}-\frac{1}{25}\)

=\(\frac{4}{25}\)

k mik nha

\(S=\frac{1}{5.6}+\frac{1}{6.7}+\frac{1}{7.8}+...+\frac{1}{24.25}\)

\(S=\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-...-\frac{1}{24}+\frac{1}{24}-\frac{1}{25}\)

\(S=\frac{1}{5}-\frac{1}{25}=\frac{4}{25}\)

Vậy \(S=\frac{4}{25}\)

a.\(\frac{3\cdot4\cdot7}{12\cdot8\cdot9}\)= \(\frac{3\cdot4\cdot7}{3\cdot4\cdot8\cdot9}\)= \(\frac{7}{72}\) 

b. \(\frac{4\cdot5\cdot6}{12\cdot10\cdot8}\)= \(\frac{4\cdot5\cdot2\cdot3}{3\cdot4\cdot5\cdot2\cdot8}\)= \(\frac{1}{8}\) 

c.\(\frac{5\cdot6\cdot7}{12\cdot14\cdot15}\)= \(\frac{5\cdot6\cdot7}{2\cdot6\cdot2\cdot7\cdot3\cdot5}\)= \(\frac{1}{12}\)

a, \(\frac{3.4.7}{12.8.9}\)= \(\frac{3.4.7}{3.4.8.9}\)= \(\frac{7}{72}\)

b, \(\frac{4.5.6}{12.10.8}\)= \(\frac{4.5.6}{3.4.2.5.8}\)= \(\frac{1}{8}\)

c, \(\frac{5.6.7}{12.14.15}\)= \(\frac{5.6.7}{2.6.2.7.3.5}\)= \(\frac{1}{12}\)

21 trên 4 bạn ạ

Cách giải là gì bn????

\(=\frac{2^3.3^3.5^3.2^3.7}{3.2^4.5^3.2.7}=\frac{2^6.5^3.3^3}{3.2^5.5^3}=2.3^2=2.9=18\)

=\(\frac{2^3\cdot3^3\cdot5^3\cdot2^3\cdot7}{3\cdot2^4\cdot5^3\cdot2\cdot7}=\frac{2^{3_{ }}\cdot3^3\cdot2^3}{3\cdot2^4\cdot2}=\frac{1728}{96}=\frac{18}{1}=18\)

2 câu trên câu nào cũng đúng. nhưng làm theo cách 2 thì nhanh hơn

\(\frac{0,8.0,04.1,25.25+0,6524+0,3476}{10.125.4.25.8}\)

\(=\frac{\left(0,8.1,25\right).\left(0,04.25\right)+\left(0,6524+0,3476\right)}{10.\left(125.8\right).\left(25.4\right)}\)

\(=\frac{1.1+1}{10.1000.100}\)

\(=\frac{1}{500000}\)

nếu mà ra phân số thì mình tính là \(\frac{2}{1000000}\)

nếu mà mình lấy 2:1000000=0,000002

chưa chắc là mình tính đúng đâu bạn nhớ tính lại nhé

chú bạn học giỏi nha

\(B=\frac{2.4+2.4.8+4.8.16+8.16.32}{3.4+2.6.8+4.12.16+8.24.32}\)

\(B=\frac{2.4+2.4.8+4.2.4.16+2.4.16.32}{3.4+2.2.3.2.4+4.3.4.16+2.4.8.3.32}\)

\(B=\frac{2.4.\left(1+8+4.16+16.32\right)}{3.4.\left(1+2.2.2+4.16+2.8.32\right)}\)

\(B=\frac{2.4.\left(1+8+4.16+16.32\right)}{3.4.\left(1+8+4.16+16.32\right)}\)

\(B=\frac{2}{3}\)

Chúc bn học tốt !!!!

ai giúp mk câu này với

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