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9 tháng 5 2021

\(a.\)

\(\dfrac{3}{10}:\left(-\dfrac{2}{3}\right)=\dfrac{3}{10}\cdot\dfrac{-3}{2}=-\dfrac{9}{20}\)

\(b.\)

\(\left(-\dfrac{7}{12}\right):\left(-\dfrac{5}{6}\right)=\left(-\dfrac{7}{12}\right)\cdot\left(-\dfrac{6}{5}\right)=\dfrac{\left(-7\right)\cdot\left(-6\right)}{12\cdot5}=\dfrac{7}{10}\)

\(c.\)

\(\left(-15\right):-\dfrac{9}{10}=\left(-15\right)\cdot-\dfrac{10}{9}=\dfrac{150}{9}=\dfrac{50}{3}\)

a) \(\dfrac{3}{10}:\dfrac{-2}{3}=\dfrac{3}{10}.\dfrac{-3}{2}=\dfrac{3.-3}{10.2}=\dfrac{-9}{20}\) 

b) \(\dfrac{-7}{12}:\dfrac{-5}{6}=\dfrac{-7}{12}.\dfrac{-6}{5}=\dfrac{-7.-6}{12.5}=\dfrac{7}{10}\) 

c)\(-15:\dfrac{-9}{10}=-15.\dfrac{-10}{9}=\dfrac{-15.-10}{9}=\dfrac{50}{3}\)

9 tháng 5 2021

\(a.\)

\(-\dfrac{5}{9}\cdot\dfrac{12}{35}=\dfrac{\left(-5\right)\cdot12}{9\cdot35}=\dfrac{-60}{315}=-\dfrac{4}{21}\)

\(b.\)

\(\left(-\dfrac{5}{8}\right)\cdot-\dfrac{6}{55}=\dfrac{\left(-5\right)\cdot\left(-6\right)}{8\cdot55}=\dfrac{30}{440}=\dfrac{3}{44}\)

\(c.\)

\(\left(-7\right)\cdot\dfrac{2}{5}=-\dfrac{14}{5}\)

\(d.\)

\(-\dfrac{3}{8}\cdot\left(-6\right)=\dfrac{-3\cdot\left(-6\right)}{8}=\dfrac{18}{8}=\dfrac{9}{4}\)

2 tháng 10 2021

\(\left(0,09\right)^3=\left(\dfrac{9}{100}\right)^3=\left[\left(\dfrac{3}{10}\right)^2\right]^3=\left(\dfrac{3}{10}\right)^6\\ \left(\dfrac{3}{10}\right)^8=\left(\dfrac{3}{10}\right)^8\\ \left(0,027\right)^2=\left(\dfrac{27}{1000}\right)^2=\left[\left(\dfrac{3}{10}\right)^3\right]^2=\left(\dfrac{3}{10}\right)^6\)

20 tháng 3 2017

101/200

20 tháng 3 2017

A=\(\dfrac{-101}{200}\)

22 tháng 6 2021

giúp em với mọi người ơi 😭😭😭😭

11 tháng 6 2023

`(1 1/4)^10 . (2/5)^20`

`=(5/4)^10 . (2/5)^20`

`=(5^10 .2^20)/(4^10 .5^20)`

`=(5^10 .4^10)/(4^10 .5^20)`

`=1/(5^10)`

`=(1/5)^10`

10 tháng 10 2017

Ta có :

\(0,0\left(8\right)=\dfrac{1}{10}.0,\left(8\right)=\dfrac{1}{10}.0,\left(1\right).8=\dfrac{1}{10}.\dfrac{1}{9}.8=\dfrac{4}{45}\)

\(0,1\left(2\right)=0,1+0,0\left(2\right)\)

\(=\dfrac{1}{10}+\dfrac{1}{10}.0,\left(2\right)=\dfrac{1}{10}+\dfrac{1}{10}.0,\left(1\right).2\)

\(=\dfrac{1}{10}+\dfrac{1}{10}.\dfrac{1}{9}.2=\dfrac{9}{90}+\dfrac{2}{90}=\dfrac{11}{90}\)

\(0,1\left(23\right)=0,1+0,0\left(23\right)=\dfrac{1}{10}+\dfrac{1}{10}.0,23\)

\(=\dfrac{1}{10}+\dfrac{1}{10}.0,\left(01\right).23\)

\(\dfrac{1}{10}+\dfrac{1}{10}.\dfrac{1}{99}.23=\dfrac{99}{990}+\dfrac{23}{990}=\dfrac{122}{990}=\dfrac{61}{495}\)

10 tháng 6 2017

\(\dfrac{34}{99};\dfrac{5}{9};\dfrac{41}{333}.\)

a:

Sửa đề: \(\dfrac{n+1}{2n+3}\)

Gọi d=ƯCLN(n+1;2n+3)

=>2n+2-2n-3 chia hết cho d

=>-1 chia hết cho d

=>d=1

=>ĐPCM

b: Gọi d=ƯCLN(4n+8;2n+3)

=>4n+8-4n-6 chia hết cho d

=>2 chia hêt cho d

=>d=1

=>ĐPCM

c: Gọi d=ƯCLN(3n+2;5n+3)

=>15n+10-15n-9 chia hết cho d

=>1 chia hết cho d

=>d=1

=>ĐPCM