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13 tháng 12 2016
a) \(\frac{1}{2}-\frac{1}{4}.\left(-\frac{6}{5}\right)\)
\(=\frac{1}{2}-\left(-\frac{3}{10}\right)\)
\(=\frac{4}{5}\)
b) \(\frac{\left(\frac{1}{9}\right)^0.3^2.9^3}{729}=\frac{1.9.729}{729}=\frac{9.729}{729}=9\)
GA
2
NN
6 tháng 12 2017
a) \(\dfrac{1}{2}-\dfrac{3}{4}.\dfrac{-6}{5}\)
\(=\dfrac{1}{2}-\dfrac{3.\left(-6\right)}{4.5}\)
\(=\dfrac{1}{2}-\dfrac{-18}{20}\)
\(=\dfrac{1}{2}+\dfrac{9}{10}\)
\(=\dfrac{5}{10}+\dfrac{9}{10}\)
\(=\dfrac{5+9}{10}\)
\(=\dfrac{14}{10}\)
\(=\dfrac{7}{5}\)
b) \(\dfrac{\dfrac{1^0}{9}.3^2.9^3}{729}\)
\(=\dfrac{9^{-1}.3^2.9^3}{729}\)
\(=\dfrac{9^{-1}.9.9^3}{729}\)
\(=\dfrac{9^{-1+1+3}}{729}\)
\(=\dfrac{9^3}{729}\)
\(=\dfrac{729}{729}\)
\(=1\)
26 tháng 2 2017
Ta có: \(A=\left[6.\left(-\frac{1}{3}\right)^2-3.\left(-\frac{1}{3}\right)+1\right]:\left(\frac{-1}{3}-1\right)\)
\(=\left(6.\frac{1}{9}-\left(-1\right)+1\right):\left(\frac{-4}{3}\right)\)
\(=\left(\frac{2}{3}+2\right).\left(\frac{-3}{4}\right)\)
\(=\frac{8}{3}.\left(-\frac{3}{4}\right)\)
\(=-2\)
\(B=\left(729-1^3\right)\left(729-3^3\right)...\left(729-125^3\right)\)
\(\Rightarrow B=\left(729-1^3\right)\left(729-3^3\right)...\left(729-9^3\right)...\left(729-125^3\right)\)
\(\Rightarrow B=\left(729-1^3\right)\left(729-3^3\right)...0...\left(729-125^3\right)\)
\(\Rightarrow B=0\)
Vì -2 < 0 nên A < B
Vậy A < B
C
0
25 tháng 7 2020
Câu a) số lớn lắm
b) \(3^{-3}\cdot3^5\cdot3^x=3^8\)
=> \(\frac{1}{27}\cdot3^5\cdot3^x=3^8\)
=> \(\frac{1}{27}\cdot3^x=3^3\)
=> \(3^x=3^3:\frac{1}{27}=3^3:\left(\frac{1}{3}\right)^3=3^3:\frac{1^3}{3^3}=3^3\cdot3^3=3^6\)
=> x = 6
b) \(\left(7x+2\right)^{-1}=3^{-2}\)
=> \(\frac{1}{7x+2}=\frac{1}{9}\)
=> 7x + 2 = 9
=> 7x = 7
=> x = 1
Bài 2:
a) \(3^4\cdot\frac{1}{729}\cdot81^3\cdot\frac{1}{9^2}\)
\(=3^4\cdot\left(\frac{1}{3}\right)^6\cdot\left(3^4\right)^3\cdot\left(\frac{1}{3}\right)^4\)
\(=3^4\cdot\left(\frac{1}{3}\right)^6\cdot3^{12}\cdot\left(\frac{1}{3}\right)^4=3^{16}\cdot\left(\frac{1}{3}\right)^{10}=\frac{3^{16}}{3^{10}}=3^6\)
b) \(\left(8\cdot2^5\right):\left(2^4\cdot\frac{1}{32}\right)=\left(2^3\cdot2^5\right):\left(2^4\cdot\left(\frac{1}{2}\right)^5\right)\)
\(=2^8:\left(2^4\cdot\frac{1^5}{2^5}\right)=2^8:\left(\frac{2^4}{2^5}\right)=2^8:2^{-1}=512\)
c) \(12^8\cdot9^{12}=\left(2^2\cdot3\right)^8\cdot\left(3^2\right)^{12}=2^{16}\cdot3^8\cdot3^{24}=2^{16}\cdot3^{32}\)
d) Tương tự
Trả lời
(-1/9)0.32.93/729
=1.32.93/93
=32=9
\(\frac{\left(-\frac{1}{9}\right)^0.3^2.3^3}{729}=\frac{1.3^5}{3^6}=\frac{1}{3}\)