Tính:
a) 253 : 52
b) \(\left(\frac{3}{7}\right)^{21}\) : \(\left(\frac{9}{49}\right)^6\)
c) 3- \(\left(\frac{-6}{7}\right)^0\) + \(\left(\frac{1}{2}\right)^2\) : 2
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30 tháng 7 2018
a) \(\left(\frac{3}{7}\right)^{21}:\left(\frac{3}{7}^3\right)^6\)
\(=\left(\frac{3}{7}\right)^{21}:\left(\frac{3}{7}\right)^{18}\)
\(=\left(\frac{3}{7}\right)^{21-18}\)
\(=\left(\frac{3}{7}\right)^3\)
\(=\frac{27}{343}\)
19 tháng 7 2016
a/\(\left(\frac{3}{7}\right)^{21}:\left(\frac{9}{49}\right)^6\)\(=\left(\frac{3}{7}\right)^{21}.\left(\frac{49}{9}\right)^6\)đơn giản rồi cộng số mũ nhá!b/ \(3-\left(-\frac{6}{7}\right)^0+\left(\frac{1}{2}\right)^2:2\)\(=3-1+\frac{1}{4}:2\)\(=2-0,125\)\(=1,875\)
k nha
14 tháng 9 2015
b, \(\left(\frac{3}{7}\right)^{21}:\left(\frac{9}{49}\right)^6=\left(\frac{3}{7}\right)^{21}:\left[\left(\frac{3}{7}\right)^2\right]^6=\left(\frac{3}{7}\right)^{21}:\left(\frac{3}{7}\right)^{12}=\left(\frac{3}{7}\right)^{21-12}=\left(\frac{3}{7}\right)^9\)
S
14 tháng 7 2016
a) \(25^3:5^2=5^6:5^2=5^4=625\)
b) \(\left(\frac{3}{7}\right)^{21}:\left(\frac{9}{49}\right)^6=\left(\frac{3}{7}\right)^{21}:\left(\frac{3}{7}\right)^{12}=\left(\frac{3}{7}\right)^9\)
c) \(3-\left(-\frac{6}{7}\right)^0+\left(\frac{1}{2}\right)^2:2=3-1+\frac{1}{8}=\frac{17}{8}\)
2 tháng 8 2015
a, \(\left(\frac{3}{7}\right)^{21}:\left(\frac{9}{49}\right)^6=\left(\frac{3}{7}\right)^{21}:\left(\frac{3}{7}\right)^{12}=\frac{3}{7}^9\)
\(a.25^3:5^2=\left(5^2\right)^3:5^2=5^6:5^2=5^{6-2}=5^4=625\)
\(b.\left(\frac{3}{7}\right)^{21}:\left(\frac{9}{49}\right)^6=\frac{3}{7}^{21}:\left(\frac{3}{7}^2\right)^6=\frac{3}{7}^{21-12}=\frac{3}{7}^9\)
\(c.3-\left(\frac{-6}{7}\right)^0+\left(\frac{1}{2}\right)^2:2=3-1+\frac{1}{4}.\frac{1}{2}=2+\frac{1}{8}=\frac{17}{8}\)
\(25^3:5^2=5^{15}:5^2=5^{13}\)
\(\left(\frac{3}{7}\right)^{21}:\left(\frac{9}{49}\right)^6=\left(\frac{3}{7}\right)^{21}:\left(\frac{3}{7}\right)^{12}=\left(\frac{3}{7}\right)^9\)