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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: \(=2^2\cdot9\cdot\dfrac{1}{6\cdot9}\cdot\dfrac{4^2}{9^2}=\dfrac{2^2}{6}\cdot\dfrac{2^4}{3^4}=\dfrac{2^6}{2\cdot3\cdot3^4}=\dfrac{2^5}{3^5}=\left(\dfrac{2}{3}\right)^5\)

b: \(=2^8\cdot\dfrac{3^4}{2^4}=3^4\cdot2^4=6^4\)

c: \(=\dfrac{\left(\dfrac{1}{2}\right)^3\cdot2^3\cdot\left(\dfrac{1}{2}\right)^2}{\left(-8\right)^2\cdot16}\cdot2^6=\dfrac{\dfrac{1}{2^2}}{64\cdot16}\cdot64=\dfrac{1}{4}:16=\dfrac{1}{64}=\left(\dfrac{1}{8}\right)^2\)

a: \(=2^2\cdot9\cdot\dfrac{1}{3^3\cdot2}\cdot\dfrac{2^4}{3^4}=\dfrac{2^4\cdot2^2}{2}\cdot\dfrac{9}{3^3\cdot3^4}=\dfrac{2^5}{3^5}=\left(\dfrac{2}{3}\right)^5\)

b: \(=2^8\cdot\dfrac{3^4}{2^4}=3^4\cdot2^4=6^4\)

c: \(=\dfrac{\dfrac{1}{2^3}\cdot\dfrac{1}{2^2}\cdot8}{\left(-8\right)^2\cdot2^4}\cdot2^6=\dfrac{1}{2^2}\cdot2^6:2^{10}=\dfrac{2^4}{2^{10}}=\dfrac{1}{2^6}=\left(\dfrac{1}{8}\right)^2\)

21 tháng 10 2017

a)  \(=\left(\frac{-1}{5}^3\right)^{100}va\left(\frac{-1}{3}^5\right)^{100}\)

\(=\left(\frac{-1}{125}\right)^{100}va\left(\frac{-1}{243}\right)^{100}\)

Mà \(\frac{-1}{125}>\frac{-1}{243}\)

\(\Rightarrow\left(\frac{-1}{5}\right)^{300}>\left(\frac{-1}{3}\right)^{500}\)

b)\(2^{27}=8^9;3^{18}=9^9\)

16 tháng 9 2017

a, \(\left(4.2\right)^5:\left(2^3.\dfrac{1}{16}\right)=8^5:\left(2^3.\dfrac{1^4}{2^4}\right)=\left(2^3\right)^5:\dfrac{2^3.1^4}{2^4}=2^{15}:\dfrac{1}{2}=2^{15}.2=2^{16}\)

\(b,\dfrac{2^2.4.32}{2^2.2^5}=\dfrac{2^2.2^4.2^5}{2^2.2^5}=2^4=16\)

16 tháng 9 2017

\(a,\dfrac{\left(4.2\right)^5}{2^3.\dfrac{1}{16}}=\dfrac{\left(2^3\right)^5}{2^3.2^{-4}}=\dfrac{2^{15}}{2^{-1}}=2^{16}\)

b,\(\dfrac{2^2.4.32}{2^2.2^5}=\dfrac{2^2.2^2.2^5}{2^2.2^5}=2^2=4\)

a: \(=\dfrac{3^3\cdot2^6}{3^{-4}\cdot2^6}=3^7\)

b: \(=\left(\dfrac{3}{7}\right)^5\cdot\left(\dfrac{3}{7}\right)\cdot\dfrac{5^6}{3^6}:\left(\dfrac{625}{343}\right)^2\)

\(=\dfrac{3^6}{7^6}\cdot\dfrac{5^6}{3^6}:\dfrac{5^8}{7^6}\)

\(=\dfrac{1}{5^2}\)

c: \(=5^{4+3}\cdot\left(\dfrac{5}{2}\right)^{-5}\cdot\dfrac{1}{25}\)

\(=5^5\cdot\left(\dfrac{2}{5}\right)^5=2^5\)

15 tháng 9 2017

\(\dfrac{81}{125}=\dfrac{3^4}{5^3}\) ; \(-\dfrac{8}{27}=-\left(\dfrac{2}{3}\right)^3\)

17 tháng 11 2021

D,       Vì 3^2=9 và -3^2=9 còn 5^2=25

17 tháng 11 2021

D

 

a: \(=\dfrac{3^3\cdot2^6}{3^{-4}\cdot2^6}=3^7\)

b: \(=\left(\dfrac{3}{7}\cdot\dfrac{5}{3}\right)^6\cdot\dfrac{5}{3}\cdot\dfrac{3}{7}:\left(\dfrac{7^3}{5^4}\right)^{-2}\)

\(=\left(\dfrac{5}{7}\right)^6\cdot\dfrac{5}{7}\cdot\left(\dfrac{5}{7}\right)^6\cdot5^2\)

\(=\left(\dfrac{5}{7}\right)^{13}\cdot5^2\)

c: \(=5^4\cdot2.5^{-5}\cdot125\cdot0.04\)

\(=5^4\cdot5\cdot\left(\dfrac{5}{2}\right)^{-5}\)

\(=5^5\cdot\left(\dfrac{2}{5}\right)^5=2^5\)