A=\(\frac{1.2.3.....20.\left(21.22.23.....39\right)}{\left(21.22.23.....39\right).40}\)

A=\(\frac{1.2.3.....20}{40}\)

A=\(1.3.4.5.....18.19\)

+2.20/40.

A=1.3.4.5.....18.19+1.

A= tự bấm máy là ra.

tk mk nha các bn.

-chúc ai tk mk học giỏi-

hết cỡ rồi ông tướng

giúp mik đi mà các bạn ơi

2/3; 5/12; 37/50; 6/7; 20/27; 2/3

Viết lại cái đề xem nào

c

giúp mình với

\(\frac{27}{62}\)

\(\dfrac{35}{210}=\dfrac{35:35}{210:35}=\dfrac{1}{6}\)

\(\dfrac{34}{68}=\dfrac{34:34}{68:34}=\dfrac{1}{2}\)

\(\dfrac{64}{720}=\dfrac{64:8}{720:8}=\dfrac{8}{90}\)

Lời giải:
$\frac{35}{210}=\frac{35}{35\times 6}=\frac{1}{6}$

$\frac{34}{68}=\frac{34}{34\times 2}=\frac{1}{2}$
$\frac{64}{720}=\frac{8\times 8}{8\times 90}=\frac{8}{90}=\frac{4\times 2}{2\times 45}=\frac{4}{45}$

Ta có: \(\frac{1010}{1008\cdot8-994}\)

\(=\frac{1010}{8064-994}=\frac{1010}{7070}=\frac17\)

\(=\frac{1\cdot3}{7\cdot3}=\frac{3}{21}\)

\(\frac{1\cdot2\cdot3+2\cdot4\cdot6+3\cdot6\cdot9+5\cdot10\cdot15}{1\cdot3\cdot6+2\cdot6\cdot12+3\cdot9\cdot18+5\cdot15\cdot30}\)

\(=\frac{1\cdot2\cdot3+1\cdot2\cdot3\cdot2\cdot2\cdot2+1\cdot2\cdot3\cdot3\cdot3\cdot3+1\cdot2\cdot3\cdot5\cdot5\cdot5}{1\cdot3\cdot6+1\cdot3\cdot6\cdot2\cdot2\cdot2+1\cdot3\cdot6\cdot3\cdot3\cdot3+1\cdot3\cdot6\cdot5\cdot5\cdot5}\)

\(=\frac{1\cdot2\cdot3\left(1+2^3+3^3+5^3\right)}{1\cdot3\cdot6\cdot\left(1+2^3+3^3+5^3\right)}=\frac26=\frac13\)

\(=\frac{1\cdot7}{3\cdot7}=\frac{7}{21}\)

Ta có:\(\frac{1.3.5......39}{21.22.23........4}=\frac{1.3.5....39.2.4.6...40}{21.22.23......40.2.4.6.....40}\)

=\(\frac{40!}{21.22....40\left(1.2.3....20\right).2^{20}}\)

=\(\frac{40!}{40!2^{20}}=\frac{1}{2^{20}}\)