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LG
6 tháng 7 2017
1. \(\dfrac{9.5^{20}.27^9-3.9^{15}:25^9}{7.3^{29}.125^6-3.3^9.15^{19}}\)
\(=\dfrac{3^2.5^{20}.3^{27}-3.3^{30}.5^{18}}{7.3^{29}.5^{18}-3^{10}.3^{19}.5^{19}}\)
\(=\dfrac{3^{29}.5^{20}-3^{31}.5^{18}}{7.3^{29}.5^{18}-3^{29}.5^{19}}\)
\(=\dfrac{3^{28}.5^{18}.\left(5^2-3^2\right)}{3^{29}.5^{18}.\left(7-5\right)}\)
\(=\dfrac{5^2-3^2}{7-5}=\dfrac{16}{2}=8\)
2.\(\left(\dfrac{1}{2}\right)^{15}.\left(\dfrac{1}{-4}\right)^{20}=\left(\dfrac{1}{2}\right)^{15}.\left(\dfrac{1}{4}\right)^{20}\)
\(=\left(\dfrac{1}{2}\right)^{15}.\left(\dfrac{1}{2}^2\right)^{20}=\left(\dfrac{1}{2}\right)^{15}.\left(\dfrac{1}{2}\right)^{40}\)
\(=\left(\dfrac{1}{2}\right)^{55}\)
3.\(\dfrac{4^5.9^4-2.6^9}{2^{10}.3^8+6^8.20}=\dfrac{2^{10}.3^8-2.2^9.3^9}{2^{10}.3^8+2^8.3^8.2^2.5}\)
\(=\dfrac{2^{10}.3^8-2^{10}.3^9}{2^{10}.3^8+2^{10}.3^8.5}=\dfrac{2^{10}.3^8\left(1-3\right)}{2^{10}.3^8\left(1+5\right)}\)
\(=\dfrac{1-3}{1+5}=\dfrac{-2}{6}=\dfrac{-1}{3}\)
Chúc học tốt!!
5 tháng 7 2017
\(\left(\dfrac{2}{3}\right)^3.\left(\dfrac{-3}{4}\right)^2.\left(-1\right)^{2013}=\dfrac{8}{27}.\dfrac{9}{16}.\left(-1\right)=-\dfrac{1}{6}\)
\(\left(\dfrac{1}{5}\right)^{15}.\left(\dfrac{1}{4}\right)^{20}=\dfrac{1}{5^{12}}.\dfrac{1}{4^{20}}=5^{-12}.4^{-20}=125^{-4}.1024^{-4}=\left(125.1024\right)^{-4}=128000^{-4}\)
5 tháng 7 2017
\(\dfrac{16^3.3^{10}+120.6^9}{4^6.3^{12}+6^{11}}=\dfrac{2^{12}.3^{10}+2^3.3.5.2^9.3^9}{2^{12}.3^{12}+2^{11}.3^{11}}=\dfrac{2^{12}.3^{10}+2^{12}.2^{10}.5}{2^{12}.3^{12}+2^{11}.3^{11}}=\dfrac{2^{12}.3^{10}\left(1+5\right)}{2^{11}.3^{11}\left(2.3+1\right)}=\dfrac{2.6}{3.7}=\dfrac{4}{7}\)
30 tháng 5 2022
\(=\dfrac{2^{18}\cdot3^3\cdot\left(3^2\cdot2\right)^7+3^{15}\cdot2^{15}}{2^{10}\cdot2^{15}\cdot3^{15}+3^{14}\cdot3\cdot5\cdot2^6}\)
\(=\dfrac{2^{25}\cdot3^{17}+3^{15}\cdot2^{15}}{2^{25}\cdot3^{15}+3^{15}\cdot5\cdot2^6}\)
\(=\dfrac{2^{15}\cdot3^{15}\left(2^{10}\cdot3^2+1\right)}{2^6\cdot3^{15}\left(2^{19}+5\cdot1\right)}=\dfrac{2^9\cdot9217}{524293}\)
5 tháng 8 2022
a: \(\Leftrightarrow x\cdot\dfrac{1}{2}-\dfrac{3}{5}x+\dfrac{13}{5}=-\dfrac{7}{5}-\dfrac{7}{10}x\)
=>3/5x=-4
hay x=-4:3/5=-20/3
b: \(\Leftrightarrow4x-6-9=5-3x-2\)
=>4x-15=-3x+3
=>7x=18
hay x=18/7
2 tháng 7 2017
a) \(\dfrac{\dfrac{7}{10}+\dfrac{3}{5}}{\dfrac{7}{10}+\dfrac{1}{2}}\) = (\(\dfrac{7}{10}+\dfrac{3}{5}\) ) : ( \(\dfrac{7}{10}+\dfrac{1}{2}\) )
= \(\dfrac{7+6}{10}\) : \(\dfrac{7+5}{10}\)
= \(\dfrac{13}{10}:\dfrac{12}{10}\)
= \(\dfrac{13}{10}.\dfrac{10}{12}\) =\(\dfrac{13}{12}\)
b) \(\dfrac{6-\dfrac{1}{\dfrac{1}{2}-\dfrac{1}{3}}}{6+\dfrac{1}{\dfrac{1}{2}-\dfrac{1}{3}}}\)
= ( 6 - \(\dfrac{1}{\dfrac{1}{2}-\dfrac{1}{3}}\) ) : ( 6 + \(\dfrac{1}{\dfrac{1}{2}-\dfrac{1}{3}}\) )
= ( 6 - \(\dfrac{1}{\dfrac{1}{6}}\) ) : ( 6 + \(\dfrac{1}{\dfrac{1}{6}}\) )
= ( 6 - 6 ) : (6 + 6) = \(\dfrac{0}{12}\) =0
8 tháng 10 2018
bài 2
\(2^x\cdot7=224\)
\(\Rightarrow2^x=224\div7\)
\(\Rightarrow2^x=32\)
\(\Rightarrow2^x=2^5\)
\(\Rightarrow x=5\)
\(\left(3^x+5\right)^2=289\)
\(\Rightarrow\left(3^x+5\right)^2=17^2\)
\(\Rightarrow3^x+5=17\)
\(\Rightarrow3^x=17-5\)
\(\Rightarrow3^x=12\)
PC
2 tháng 10 2019
\(\frac{9^{10}\cdot27^7}{81^7\cdot3^{15}}=\frac{3^{20}\cdot3^{21}}{3^{28}\cdot3^{15}}=\frac{3^{41}}{3^{43}}=\frac{1}{9}\)
\(\frac{2^{10}\cdot3^{13}\cdot16^3}{4^{10}\cdot9^6}=\frac{2^{10}\cdot3^{13}\cdot2^{12}}{2^{20}\cdot3^{12}}=\frac{2^{22}\cdot3^{13}}{2^{20}\cdot3^{12}}=2^2\cdot3=12\)
20 tháng 5 2022
a: \(\Leftrightarrow3^x\cdot\left(\dfrac{2}{3}\cdot3-7\right)=405\)
\(\Leftrightarrow3^x=-81\)(vô lý)
b: \(\left(0,4x-1,3\right)^2=5,29\)
=>0,4x-1,3=2,3 hoặc 0,4x-1,3=-2,3
=>0,4x=3,6 hoặc 0,4x=-1
=>x=9 hoặc x=-2,5
c: \(5\cdot2^{x+1}\cdot2^{-2}-2^x=284\)
\(\Leftrightarrow2^x\cdot5\cdot2\cdot2^{-2}-2^x=284\)
\(\Leftrightarrow2^x\cdot\left(\dfrac{5}{2}-1\right)=284\)
\(\Leftrightarrow2^x=\dfrac{568}{3}\)(vô lý)
d: \(\Leftrightarrow4^x\left(1+4^3\right)=4160\)
\(\Leftrightarrow4^x=64\)
hay x=3
28 tháng 6 2022
a: \(=\dfrac{5\cdot\left(8-6\right)}{10}=\dfrac{5\cdot2}{10}=1\)
b: \(\dfrac{\left(-4\right)^2}{5}=\dfrac{16}{5}\)
\(B=\dfrac{3}{7}-\dfrac{1}{5}-\dfrac{3}{7}=-\dfrac{1}{5}\)
c: \(C=\left(6-2.8\right)\cdot\dfrac{25}{8}-\dfrac{8}{5}\cdot4\)
\(=\dfrac{16}{5}\cdot\dfrac{25}{8}-\dfrac{32}{5}\)
\(=5\cdot2-\dfrac{32}{5}=10-\dfrac{32}{5}=\dfrac{18}{5}\)
d: \(D=\left(\dfrac{-5}{24}+\dfrac{18}{24}+\dfrac{14}{24}\right):\dfrac{-17}{8}\)
\(=\dfrac{27}{24}\cdot\dfrac{-8}{17}=\dfrac{-9}{8}\cdot\dfrac{8}{17}=\dfrac{-9}{17}\)
\(=\dfrac{2^7\left(3+2^3\right)}{13.2^7-7.2^7}=\dfrac{2^7\left(3+8\right)}{2^7\left(13-7\right)}=\dfrac{11}{6}\)