\(\frac{13}{10}\times\frac{15}{7}-\frac{8}{7}\times\frac{4}{3}+2=\frac{39}{14}-\frac{32}{21}+2=\frac{137}{42}\)

\(\frac{13}{10}.\frac{15}{7}-\frac{8}{7}.\frac{4}{3}+2\)

\(=\frac{39}{14}-\frac{32}{21}+2\)

\(=\frac{117}{42}-\frac{64}{42}+\frac{84}{42}\)

\(=\frac{117-64+84}{42}\)

\(=\frac{137}{42}\)

cảm ơn nhé

\(\frac{2^{13}\cdot3^7}{4^7\cdot9^3}=\frac{2^{13}\cdot3^7}{\left[2^2\right]^7\cdot\left[3^2\right]^3}=\frac{2^{13}\cdot3^7}{2^{14}\cdot3^6}=2^{-1}\cdot3=\frac{1}{2}\cdot3=\frac{3}{2}\)

a) Ta có: \(\dfrac{3}{5\cdot7}+\dfrac{3}{7\cdot9}+...+\dfrac{3}{59\cdot61}\)

\(=\dfrac{3}{2}\left(\dfrac{2}{5\cdot7}+\dfrac{2}{7\cdot9}+...+\dfrac{2}{59\cdot61}\right)\)

\(=\dfrac{3}{2}\left(\dfrac{1}{5}-\dfrac{1}{61}\right)\)

\(=\dfrac{3}{2}\cdot\dfrac{56}{305}=\dfrac{84}{305}\)

a)

b) câu b, bạn vt hơi khó hiểu

\(\dfrac{3}{7}.\dfrac{9}{36}-\dfrac{1}{14}.\dfrac{1}{13}\)

\(=\dfrac{3.9}{7.36}-\dfrac{1.1}{14.13}\)

\(=\dfrac{3}{28}-\dfrac{1}{182}=\dfrac{37}{364}\)

3/7 . 9/36 - 1/14 . 1/13

= 3/28 - 1/182 

= 37/364

37/364

2\3x-780\11:[13\2.(1\3.5+1\5.7+1\7.9+1\9.11]=-5

2\3x-780\11:[13\2.(1\3-1\5+1\5-1\7+....+1\9-1\11)]=-5

2\3x-780\11:[13\2.(1\3-1\11)]=-5

2\3x-780\11:[13\2.8\33]=-5

2\3x-780\11:52\33=-5

2\3x-525\13=-5

2\3x=-5+525\13

2\3x=460\13

x=460\13:2\3

x=690\13