C1:

`5/8 xx (1/5 +2)`

`=5/8 xx (1/5 +10/5)`

`=5/8 xx 11/5`

`=11/8`

C2:

`5/8 xx (1/5 +2)`

`=5/8 xx 1/5 + 5/8 xx 2`

`=1/8 + 10/8`

`=11/8`

ai giúp mik với ak mik cần gấp

\(\dfrac{1}{1.4}+\dfrac{1}{4.2}+\dfrac{1}{2.8}+\dfrac{1}{8.4}+\dfrac{1}{4.16}+\dfrac{1}{16.8}\)

= \(\dfrac{1}{4}.\left(1+\dfrac{1}{2}+\dfrac{1}{4}+\dfrac{1}{8}+\dfrac{1}{16}+\dfrac{1}{32}\right)\)

= \(\dfrac{1}{4}.\left(\dfrac{3}{2}+\dfrac{3}{8}+\dfrac{3}{32}\right)\)

= \(\dfrac{1}{4}.\dfrac{3}{2}\left(1+\dfrac{1}{4}+\dfrac{1}{16}\right)\)

= \(\dfrac{1}{4}.\dfrac{3}{2}\left(\dfrac{16}{16}+\dfrac{4}{16}+\dfrac{1}{16}\right)\)

= \(\dfrac{3}{8}.\dfrac{21}{16}\)

= \(\dfrac{63}{128}\)

\(\frac{1}{8}.\frac{4}{5}-1=\frac{1}{10}-1=\frac{-9}{10}\)

Dễ :v

1/8x4/5-1= -9/10

7

Câu 1:

A={1;3;5;7;9}

Câu 2: 

A. 24 x 82 + 24 x 18 - 100 

= 24 x (82 + 18) - 100

= 24 x 100 - 100

= 2400 - 100 = 2300

B.12 + 3 [ 39 - (5 - 2 )² ]

= 12 + 3. [39 - 3² ]

= 12 + 3 . [39-9]

= 12 + 3.30

= 12 + 90 = 102

\(3x+2x=\frac{5}{8}.\frac{4}{3}\)

\(\Rightarrow5x=\frac{5}{6}\)

\(\Rightarrow x=\frac{5}{6}:5\)

\(\Rightarrow x=\frac{1}{6}\)

Vậy x = \(\frac{1}{6}\)

\(3x+2x=\frac{5}{8}.\frac{4}{3}\)

\(5x=\frac{5}{6}\)

\(x=\frac{5}{6}:5\)

\(x=\frac{1}{6}\)

bạn cho mk hỏi 5/8x4/3 là ntn 

bạn có thể viết rõ hơn ko 

May tinh la hop li thuan tien nhat nha bn

a) = 4x ( 12 + 1 ) +5

    = 4 x 13 + 5

     =  57

b)= (8x4 + 8x6) +8x 5

  =     8x 10       + 8x5

  =       80          +  40

  = 120 

c) = 2 + 3x2 + 4x2 + 3x2

     = 2 + ( 2 x 10 )

     =  2    + 20 

      =     22

hiểu ý giang ho dai ca roi

bạn quý chết thì có

\(\frac{7}{9}+\frac{6}{7}\times\frac{4}{5}=\frac{7}{9}+\frac{24}{35}=\frac{361}{315}\)

\(\frac{21}{23}+\frac{4}{5}:\frac{6}{8}=\frac{21}{23}+\frac{16}{15}=\frac{548}{345}\)

\(\frac{5}{8}\times\frac{4}{9}:\frac{2}{3}=\frac{5}{18}:\frac{2}{3}=\frac{5}{12}\)

\(\frac{7}{12}+\frac{5}{6}-\frac{21}{24}=\frac{14}{24}+\frac{20}{24}-\frac{21}{24}=\frac{11}{24}\)

b, 

    \(\frac{21}{23}+\frac{4}{5}:\frac{6}{8}=\frac{21}{23}+\frac{4}{5}.\frac{8}{6}=\frac{21}{23}+\frac{16}{15}=1\frac{338}{345}\)

c,

    \(\frac{5}{8}.\frac{4}{9}.\frac{3}{2}=\frac{5}{12}\)

d,

    \(\frac{7}{12}+\frac{5}{6}-\frac{21}{24}=\frac{14}{24}+\frac{20}{24}-\frac{21}{24}=\frac{13}{24}\)

chán thật