=27.(18+103-120)/33.(15+12)

= 27.1/33.27

=1/33

\(=\frac{27\left(18+103-120\right)}{33\left(15+12\right)}\)

\(=\frac{27\times1}{33\times27}\)

\(=\frac{1}{33}\)

Bài 2:

\(=\left(\dfrac{1}{5}+\dfrac{4}{5}\right)+\left(\dfrac{1}{3}+\dfrac{2}{3}\right)+\left(\dfrac{1}{4}+\dfrac{1}{4}\right)=2+\dfrac{1}{2}=\dfrac{5}{2}\)

Bài 1: 

150/120+15/27=5/4+5/9=45/36+20/36=65/36

42/49+56/84=6/7+2/3=9/21+14/21=23/21

\(\frac{27.18+27.103-120.27}{15.33+33.12}\)

\(=\frac{27\left(18+103-120\right)}{33\left(15+12\right)}\)

\(=\frac{27.1}{33.27}\)

\(=\frac{1}{33}\)

\(\frac{1}{33}\)

Nhanh lên giúp mình với

Mị ko. Biết

Ta có:

\(A=\frac{1}{10}+\frac{1}{15}+\frac{1}{21}+...+\frac{1}{120}\)

\(=\frac{2}{20}+\frac{2}{30}+\frac{2}{42}+...+\frac{2}{240}\)

\(=\frac{2}{4.5}+\frac{2}{5.6}+\frac{2}{6.7}+...+\frac{2}{15.16}\)

\(=2.\left(\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}+...+\frac{1}{15.16}\right)\)

\(=2.\left(\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+...+\frac{1}{15}-\frac{1}{16}\right)\)

\(=2.\left(\frac{1}{4}-\frac{1}{16}\right)\)

\(=2.\left(\frac{4}{16}-\frac{1}{16}\right)\)

\(=2.\frac{3}{16}=\frac{3}{8}\)

= 3/8 nhe

3/8 nhé

a) Ư (15) = {1;3;5;15}

Ư (27) = {1;3;9;27}

ƯC (15; 27) = {1;3}

b) ƯC (16; 20; 30) = {1;2}

c) BC (25; 39) = {0;975;1950;…}

d) BC (100; 120; 140) = {0;4200;…}