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Khách
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K
5 tháng 7 2019
a) \(9^8=\left(3^2\right)^8=3^{16}\)
\(27^3=\left(3^3\right)^3=3^9\)
\(81^2=\left(3^4\right)^2=3^8\)
\(\Leftrightarrow3^{16}:\left(3^9.3^8\right)\)
\(\Leftrightarrow3^{16}:3^{17}\)
\(\Leftrightarrow3^{-1}=\frac{1}{3}\)
NC
29 tháng 8 2020
Bài làm:
Ta có: \(\frac{9^2.\left(-4\right)^5.72}{5.\left(-6\right)^6}\cdot\frac{6^3.81.\left(-4\right)}{\left(-8\right)^6.3^9}\)
\(=\frac{3^2.-2^{10}.2^3.3^2.2^3.3^3.3^4.-2^2}{5.2^3.3^3.2^{18}.3^9}\)
\(=\frac{2^{18}.3^{11}}{2^{21}.3^{12}.5}\)
\(=\frac{1}{2^3.2.5}=\frac{1}{120}\)
29 tháng 8 2020
\(\frac{25^5.2^{10}}{20^4.5^4}\)
=\(\frac{25^5.2^{10}}{20^4.25^2}\)
=\(\frac{25^3.2^{10}}{20^4}\)
=\(\frac{25^3.1024}{160000}\)
=\(\frac{25^3.4}{25^2}\)
=\(25.4\)
=100
QT
1
HQ
Hà Quang Minh
Giáo viên
10 tháng 10 2023
a) Cách 1: \(73 - \left( {2 - 9} \right) = 73 - 2 + 9 = 80\);
Cách 2: \(73 - \left( {2 - 9} \right) = 73 -(-7)=73+7 = 80\)
b) Cách 1: \(\left( { - 45} \right) - \left( {27 - 8} \right) = \left( { - 45} \right) - 27+8 =-72+8=- 64\)
Cách 2: \(\left( { - 45} \right) - \left( {27 - 8} \right) = \left( { - 45} \right) - 19 = - 64\)
22 tháng 7 2021
a) Ta có: \(\dfrac{5}{8}+\dfrac{3}{17}+\dfrac{4}{18}+\dfrac{20}{-17}+\dfrac{-2}{9}+\dfrac{21}{56}\)
\(=\left(\dfrac{3}{17}-\dfrac{20}{17}\right)+\left(\dfrac{2}{9}-\dfrac{2}{9}\right)+\left(\dfrac{5}{8}+\dfrac{3}{8}\right)\)
\(=-1+1=0\)
b) Ta có: \(\left(\dfrac{9}{16}+\dfrac{8}{-27}\right)+\left(1+\dfrac{7}{16}+\dfrac{-19}{27}\right)\)
\(=\left(\dfrac{9}{16}+\dfrac{7}{16}\right)+\left(\dfrac{-8}{27}-\dfrac{19}{27}\right)+1\)
=1-1+1=1
22 tháng 3 2017
13)\(\dfrac{45}{8}\left(\dfrac{4}{15}-\dfrac{7}{8}\right)+\dfrac{45}{8}\left(\dfrac{11}{15}+\dfrac{9}{8}\right)\)
=\(\dfrac{45}{8}\left(\dfrac{4}{15}-\dfrac{7}{8}+\dfrac{11}{15}+\dfrac{9}{8}\right)\)
=\(\dfrac{45}{8}\left[\left(\dfrac{4}{15}+\dfrac{11}{15}\right)-\left(\dfrac{7}{8}-\dfrac{9}{8}\right)\right]\)
=\(\dfrac{45}{8}.\dfrac{5}{4}\)=\(\dfrac{225}{32}\)
14)\(\dfrac{15}{7}\left(\dfrac{49}{35}-\dfrac{27}{8}\right)-\left(\dfrac{2}{5}-\dfrac{27}{4}\right):\dfrac{7}{15}\)
=\(\dfrac{15}{7}\left(\dfrac{49}{35}-\dfrac{27}{8}\right)-\left(\dfrac{2}{5}-\dfrac{27}{4}\right).\dfrac{15}{7}\)
=\(\dfrac{15}{7}\left[\left(\dfrac{49}{35}-\dfrac{27}{8}\right)-\left(\dfrac{2}{5}-\dfrac{27}{4}\right)\right]\)
=\(\dfrac{15}{7}\left(\dfrac{49}{35}-\dfrac{27}{8}-\dfrac{2}{5}+\dfrac{27}{4}\right)\)
=\(\dfrac{15}{7}.\dfrac{35}{8}\)=\(\dfrac{75}{8}\)
NN
16 tháng 2 2023
\(C=\dfrac{5\times2^{12}\times3^8-3^9\times2^{12}}{2^2\times2^{13}\times3^8+2\times2^{12}\times\left(-3^9\right)}=\dfrac{3^8\times2^{12}\times\left(5-3\right)}{2^{15}\times3^8+2^{13}\times\left(-3\right)^9}\)
\(=\dfrac{3^8\times2^{12}\times2}{2^{13}\times3^8\times\left(4-3\right)}=\dfrac{1}{1}=1\)
\(#PaooNqoccc\)
PA
8 tháng 7 2016
\(B=8^3\times81^4\div9^6\times32=\left(2^3\right)^3\times\left(3^4\right)^4\div\left(3^2\right)^6\times2^5=2^9\times3^{16}\div3^{12}\times2^5=2^{14}\times3^4\)
8 tháng 7 2016
\(8^3.81^4:9^6.32=\left(2^3\right)^3.\left(3^4\right)^4:\left(3^2\right)^6.2^5=2^9.3^{16}:3^{12}.2^5=\left(2^9.2^5\right).\left(3^{16}:3^{12}\right)=2^{14}.3^4\)
MT
0
#)Giải :
\(9^8:\left(27^3.81^2\right)=\left(3^2\right)^8:\left[\left(3^3\right)^3.\left(3^4\right)^2\right]=3^{16}:\left[3^9.3^8\right]\)
Đến đây ez rùi ^^
98:(273.812) = 98:(33x3.34x2)=98:317= \(\frac{1}{3^9}\)