`a, 2/3 + 1/5 . 10/7`

`= 2/3 + 10/35`

`=2/3 +2/7`

`=14/21 + 6/21`

`=20/21`

`b, 2/7 + 5/7 . 14/25`

`=  2/7 +2/5`

`= 10/35+14/35`

`= 24/35`

`c, 7/12 - 27/7 . 1/18`

`= 7/12 - 3/14`

`= 31/84`

`d, 3/10 . (-5/6) - 1/8`

`= -1/4 -1/8`

`= -2/8 -1/8`

`= -3/8`

a)

\(\dfrac{2}{3}+\dfrac{1}{5}.\dfrac{10}{7}\)

\(=\dfrac{2}{3}+\dfrac{2}{7}\)

\(=\dfrac{14}{21}+\dfrac{6}{21}\)

\(=\dfrac{20}{21}\)

b)

\(\dfrac{2}{7}+\dfrac{5}{7}.\dfrac{14}{25}\)

\(=\dfrac{2}{7}+\dfrac{2}{5}\)

\(=\dfrac{10}{35}+\dfrac{14}{35}\)

\(=\dfrac{24}{35}\)

c)

\(\dfrac{7}{12}-\dfrac{27}{7}.\dfrac{1}{18}\)

\(=\dfrac{7}{12}-\dfrac{3}{14}\)

\(=\dfrac{98}{168}-\dfrac{36}{168}\)

\(=\dfrac{31}{84}\)

d)

\(\dfrac{3}{10}.\left(-\dfrac{5}{6}\right)-\dfrac{1}{8}\)

\(=-\dfrac{1}{4}-\dfrac{1}{8}\)

\(=-\dfrac{2}{8}-\dfrac{1}{8}\)

\(=\dfrac{-3}{8}\)

phân số nào bn

19/10=1.9

14/28 : 7/18 x 6/5 + 3/10

= 9/7 x 6/5 + 3/10

= 54/35 + 3 / 10

=108/70 + 21/70

= 129/70

Tk mk nha

\(\frac{14}{27}:\frac{7}{18}x\frac{6}{5}+\frac{3}{10}=\frac{4}{3}x\frac{6}{5}+\frac{3}{10}=\frac{8}{5}+\frac{3}{10}=\frac{19}{10}\)

=4/3x6/5+3/10

=8/5+3/10

=19/10

19/10

\(\frac{14}{27}:\frac{7}{18}\cdot\frac{6}{5}+\frac{3}{10}\)

\(=\frac{14}{27}\cdot\frac{18}{7}\cdot\frac{6}{5}+\frac{3}{10}\)

\(=\frac{14\cdot18\cdot6}{27\cdot7\cdot5}+\frac{3}{10}\)

\(=\frac{2\cdot7\cdot9\cdot2\cdot3\cdot2}{3\cdot9\cdot7\cdot5}+\frac{3}{10}\)

\(=\frac{8}{5}+\frac{3}{10}\)

\(=\frac{16}{10}+\frac{3}{10}\)

\(=\frac{19}{10}\)

Bài 2. > , < ,  = ?

5/7 < 4/3             2/5 < 6/10            1/4 = 3/12                27/36 >

2/9           7/6 > 7/9

7/2 = 2/7        15/23 < 1                  27/9 > 2          14/15 < 1          51/17 < 4

sai rôi

bạn ghi lại đề đi bạn! Khó hiểu quá!

\(a,81^3=\left(9^2\right)^3=9^6\)

Vì \(9^{27}>9^6\) nên \(9^{27}>81^3\)

\(b,5^{14}=\left(5^2\right)^7=25^7\)

Vì \(25^7< 27^7\) nên \(5^{14}< 27^7\)

\(c,10^{30}=\left(10^3\right)^{10}=1000^{10}\)

\(2^{100}=\left(2^{10}\right)^{10}=1024^{10}\)

Vì \(1000^{10}< 1024^{10}\) nên \(10^{30}< 2^{100}\)