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VT
4
15 tháng 7 2018
\(81^3\cdot\frac{1}{9^2}:3^3\)
\(=\left(9^2\right)^3\cdot\frac{1}{9^2}:3^3\)
\(=9^6\cdot\frac{1}{9^2}:3^3\)
\(=9^4:3^3\)
\(=3^8:3^3=3^5\)
ND
1
15 tháng 7 2018
\(a,81^3\cdot\frac{1}{9^2}:3^3=\left(9^2\right)^3\cdot\frac{1}{9^2}:3^3=9^6\cdot\frac{1}{9^2}\cdot\frac{1}{3^3}=\frac{9^6}{9^2}\cdot\frac{1}{3^3}=9^4\cdot\frac{1}{3^3}=\left(3^2\right)^4\cdot\frac{1}{3^3}=\frac{3^8}{3^3}=3^5\)
\(b,625^4:25^2=\left(5^4\right)^4:\left(5^2\right)^2=5^{16}:5^4=5^{12}\)
4 tháng 7 2017
\(3^2\times\frac{1}{243}\times81^2\times\frac{1}{3^3}\)
\(=3^2\times\frac{1}{3^5}\times\left(3^4\right)^2\times\frac{1}{3^3}\)
\(=\left(3^2\times3^8\right)\times\left(\frac{1}{3^5}\times\frac{1}{3^3}\right)\)
\(=3^{10}\times\frac{1}{3^8}\)
\(=3^2\)
\(=9\)
\(\left(4\times2^5\right)\div\left(2^3\times\frac{1}{6}\right)\)
\(=\left(2^2\times2^5\right)\div\left(2^3\times\frac{1}{2\times3}\right)\)
\(=2^7\div2^2\times3\)
\(=2^5\times3\)
\(=96\)
19 tháng 4 2020
\(3^2.\frac{1}{243}.81^2.\frac{1}{3^3}\)
\(=3^2.\frac{1}{3^5}.\left(3^4\right)^2.\frac{1}{3^3}\)
\(=\left(3^2.3^8\right).\left(\frac{1}{3^5}.\frac{1}{3^3}\right)\)
\(=3^{10}.3^{-8}\)
\(=3^2=9\)
\(\left(4.2^5\right):\left(2^3.\frac{1}{6}\right)\)
\(=2^7:2^2.3\)
\(=2^5.3\)
\(=96\)
13 tháng 7 2017
\(7^2.49^3.7^7=7^2.\left(7^2\right)^3.7^7=7^2.7^6.7^7=7^{15}\)
\(3^5.9^4.27^2.81=3^5.\left(3^2\right)^4.\left(3^3\right)^2.3^4=3^5.3^8.3^6.3^4=3^{23}\)
13 tháng 7 2017
a) \(7^2.49^3.7^7=7^2.7^6.7^7=7^{15}\)
b) \(3^5.9^4.27^2.81=3^5.3^8.3^6.3^4=3^{23}\)
MT
4 tháng 8 2018
\(a)\) \(427-98=329\)
\(b)\) \(2\cdot19\cdot15+3\cdot43\cdot10+62\cdot80\)
\(=\left(2\cdot15\right)\cdot19+\left(3\cdot10\right)\cdot43+62\cdot80\)
\(=30\cdot19+30\cdot43+62\cdot80\)
\(=30\cdot\left(19+43\right)+62\cdot80\)
\(=30\cdot62+62\cdot80\)
\(=62\cdot\left(30+80\right)\)
\(=62\cdot110=6820\)
\(c)\) Đặt \(M=\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+\frac{1}{81}+\frac{1}{243}+\frac{1}{729}\)
\(=\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+\frac{1}{3^4}+\frac{1}{3^5}+\frac{1}{3^6}\)
\(\Rightarrow3M=1+\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+\frac{1}{3^4}+\frac{1}{3^5}\)
\(\Rightarrow3M-M=\left(1+\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+\frac{1}{3^4}+\frac{1}{3^5}\right)-\left(\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+\frac{1}{3^4}+\frac{1}{3^5}+\frac{1}{3^6}\right)\)
\(\Rightarrow2M=1-\frac{1}{3^6}\)
\(\Rightarrow M=\frac{728}{2\cdot729}=\frac{364}{729}\)
Vậy \(M=\frac{364}{729}\)
TV
17 tháng 4 2019
G = \(\frac{2^2}{1.3}\).\(\frac{3^2}{2.4}\).\(\frac{4^2}{3.5}\).....\(\frac{50^2}{49.51}\)
=> G = \(\frac{2.2}{1.3}\).\(\frac{3.3}{2.4}\).\(\frac{4.4}{3.5}\).....\(\frac{50.50}{49.51}\)
=> G = \(\frac{2.2.3.3.4.4.....50.50}{1.2.3.3.4.4.....50.51}\)
=> G = \(\frac{2.50}{1.51}\)
=> G = \(\frac{100}{51}\)
\(3^2\cdot\frac{1}{243}\cdot81^2\cdot\frac{1}{3^2}=3^2\cdot\frac{1}{3^5}\cdot3^8\cdot\frac{1}{3^2}=3^{10}\cdot\frac{1}{3^7}=3^3\)