(√7)mũ 2=mấy?
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\(\left(\frac{15}{7}\right)^2+\left(\frac{20}{7}\right)^2=\frac{225}{49}+\frac{400}{49}=\frac{625}{49}\)
a) \(7^5.7^6=7^{5+6}=7^{11}\)
b) \(5^{20}.5=5^{20+1}=5^{21}\)
c) \(7^9:7=7^{9-1}=7^8\)
d) \(25^3.5^2=\left(5^2\right)^3.5^2=5^{2.3}.5^2=5^6.5^2=5^{6+2}=5^8\)
1. 2x=16\(\Rightarrow\)X=4
2. 22x-1=27
\(\Rightarrow\)27=22.4-1
Vậy x =4
a;
A = 109 + 108 + 107
A = 107.(102 + 10 + 1)
A = 106.2.5.(100 + 10 + 1)
A = 106.2.5.111
A = 106.2.555 ⋮ 555 (đpcm)
b;
B = 817 - 279 - 919
B = 914 - 39.99 - 919
B = 914 - 3.38.99 - 919
B = 914 - 3.94.99 - 919
B = 914 - 3.913 - 919
B = 913.(9 - 3 - 96)
B = 913.(9 - 3 - \(\overline{..1}\))
B = 913.(6 - \(\overline{..1}\))
B = 913.\(\overline{..5}\)
B ⋮ 9; B ⋮ 5
B \(\in\) BC(9; 5) = 9.5 = 45
B ⋮ 45 (đpcm)
\(=\left(2^{78}+2^{78}.2+2^{78}.4\right):\left(2^{75}.4+2^{75}.2+2^{75}\right)\)
\(=\left[2^{78}.\left(1+2+4\right)\right]:\left[2^{75}\left(1+2+4\right)\right]\)
\(=\frac{2^{78}.\left(1+2+4\right)}{2^{75}.\left(1+2+4\right)}\)
\(=2^3=8\)
\(2^{x-3}=128\Leftrightarrow2^{x-3}=2^7\Rightarrow x-3=7\Leftrightarrow x=10\)
\(\left(x+6\right)^4=4096\Leftrightarrow\left(x+6\right)^4=2^{12}=\left(2^3\right)^4=8^4\Rightarrow x+6=8\Leftrightarrow x=2\)
\(2^{2018}=\left(2^4\right)^{504}.2^2==16^{504}.4< 16^{900}\\ \)
\(17^{20}>16^{20}=\left(4^2\right)^{20}=4^{40}\)
\(3^{444}=\left(3^4\right)^{111}=81^{111}>64^{111}=\left(4^3\right)^{111}=4^{333}\\ \)
7
= 7