150/101 

làm cụ thể được không Yumi

đáp án là 150/101. cách giải hơi dài nên tớ không viết,thông cảm nha!

150/101

Bạn xem lại đề.

chx hỉu cho lắm

=335510

335510

\(\frac29+\frac{2}{45}+\frac{2}{105}+\frac{2}{189}+\cdots+\frac{2}{1725}\)

\(=\frac23\left(\frac13+\frac{1}{15}+\frac{1}{35}+\frac{1}{63}+\cdots+\frac{1}{575}\right)\)

\(=\frac23\times\frac12\times\left(\frac{2}{1\times3}+\frac{2}{3\times5}+\ldots+\frac{2}{23\times25}\right)\)

\(=\frac13\times\left(1-\frac13+\frac13-\frac15+\cdots+\frac{1}{23}-\frac{1}{25}\right)=\frac13\times\left(1-\frac{1}{25}\right)\)

\(=\frac13\times\frac{24}{25}=\frac{8}{25}\)

a) \(\dfrac{1}{9}\times\dfrac{4}{7}+\dfrac{1}{9}\times\dfrac{3}{7}=\dfrac{1}{9}\times\left(\dfrac{4}{7}+\dfrac{3}{7}\right)=\dfrac{1}{9}\times1=\dfrac{1}{9}\)

b) \(\dfrac{5}{13}\times\dfrac{189}{18}-\dfrac{5}{13}\times\dfrac{9}{18}=\dfrac{5}{13}\times\left(\dfrac{189}{18}-\dfrac{9}{18}\right)=\dfrac{5}{13}\times\dfrac{180}{18}=\dfrac{5}{13}\times10=\dfrac{50}{13}\)

c) \(\dfrac{12}{7}:\dfrac{4}{9}+\dfrac{4}{7}:\dfrac{4}{9}=\dfrac{12}{7}\times\dfrac{9}{4}+\dfrac{4}{7}\times\dfrac{9}{4}=\left(\dfrac{12}{7}+\dfrac{4}{7}\right)\times\dfrac{9}{4}=\dfrac{16}{7}\times\dfrac{9}{4}=\dfrac{144}{28}=\dfrac{36}{7}\)

cảm ơnnn aaa