4x 11 x 3/4 x 9/121 = ( 4x 3/4) x (11 x 9/121) = 3 x 9/11 = 27/11

\(\frac{121}{x}=\frac{11}{9}\)

=> 121 : 11 = 11 => x = 9 . 11 = 99

\(\frac{x}{20}=\frac{12}{30}=\frac{2}{5}\)

=> 20 : 5 = 4 => x = 2 . 4 = 8

****

\(=\dfrac{4\left(\dfrac{1}{11}+\dfrac{1}{121}-\dfrac{1}{12321}\right)}{9\left(\dfrac{1}{11}+\dfrac{1}{121}-\dfrac{1}{12321}\right)}=\dfrac{4}{9}\)

1/9-5/6-4/7/12-1/35-10

mk cũng ko biết bn à

ko bt thì bl lm j

Sửa đề: \(D=\frac{1}{10\cdot11}+\frac{1}{11\cdot12}+\cdots+\frac{1}{99\cdot100}\)

\(=\frac{1}{10}-\frac{1}{11}+\frac{1}{11}-\frac{1}{12}+\cdots+\frac{1}{99}-\frac{1}{100}\)

\(=\frac{1}{10}-\frac{1}{100}=\frac{10}{100}-\frac{1}{100}=\frac{9}{100}\)

=>D là số hữu tỉ

\(C=0,3\cdot12,8+0,3\cdot7,2\)

\(=0,3\cdot\left(12,8+7,2\right)\)

\(=0,3\cdot20=6\)

=>C là số hữu tỉ

\(E=\frac{\frac{4}{11}+\frac{4}{121}-\frac{4}{12321}}{\frac{9}{11}+\frac{9}{121}-\frac{9}{12321}}=\frac{4\left(\frac{1}{11}+\frac{1}{121}-\frac{1}{12321}\right)}{9\left(\frac{1}{11}+\frac{1}{121}-\frac{1}{12321}\right)}=\frac49\)

=>E là số hữu tỉ

Ta có: \(B=\frac{4}{15}\cdot\frac{-25}{24}=\frac{4\cdot\left(-25\right)}{15\cdot24}=\frac{-100}{360}=\frac{-5}{18}\)

=>B là số hữu tỉ

121 x 34 + 11 x 11 x 50 + 121 x 26

= 121 x 34 + 121 x 50 + 121 x 26

= 121 x (34 + 50 + 26)

= 121 x 110

= 13 310

      121 x 34 + 11 x 11 x 50 + 121 x 26

= 121 x ( 34 + 26 ) + 11 x 11 x 50

= 121 x  ( 34 + 26 ) +     121  x 50

= 121 x ( 34 + 26 + 50 )

= 121 x 110

= 13 310

\(\frac{5-\frac{5}{3}+\frac{5}{9}-\frac{5}{27}}{8-\frac{8}{3}+\frac{8}{9}-\frac{8}{27}}:\frac{15-\frac{15}{11}+\frac{15}{121}}{16-\frac{16}{11}+\frac{16}{121}}\)

\(=\frac{5\left(1-\frac{1}{3}+\frac{1}{9}-\frac{1}{27}\right)}{8\left(1-\frac{1}{3}+\frac{1}{9}-\frac{1}{27}\right)}:\frac{15\left(1-\frac{1}{11}+\frac{1}{121}\right)}{16\left(1-\frac{1}{11}+\frac{1}{121}\right)}\)

\(=\frac{5}{8}:\frac{15}{16}\)

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

2/3

Tk mk nha

a,( 3/29 - 1/5 ) x 29/3

=(15/145-29/145)x29/3

=(-14/145)x29/3

=-406/435

=-14/15

b,4 x 11 x 3/4 x 9/121

=4 x 11 x 3x9/1x1x4x121

=1188/484

=59/242

k mk nha

A /  ( 3/29 - 1/5 ) x 29/3              = -14/145 x 29/3                  = -14/15                                                                                                                 B/   4 x 11 x 3/4 x 9/121                = (4 x 11) x ( 3/4 x 9/121 )                 = 44 x 27/484                =27/11                                                                                                         xong rồi đó