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a) \(3^{39}\) và \(11^{21}\)
\(\Rightarrow3^{39}=3^{13.3}=1594323^3\)
\(\Rightarrow11^{21}=11^{7.3}=194487171^3\)
Nên \(3^{39}< 11^{21}\)
b) \(199^{20}\) và \(2003^{15}\)
\(\Rightarrow199^{20}=199^{4.5}=1568239201^5\)
\(\Rightarrow2003^{15}=8036054027^5\)
Nên \(199^{20}< 2003^{15}\)
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a) 19920 < 20020
200015 < 200315
ta có : 20020 = ( 8 . 25 ) 20 = ( 23 . 52 )20 = 260 . 540
200015 = ( 2 .103 ) 15 = ( 24 . 53 ) 15 = 260 . 545
Vì 40 < 45 nên 260 . 540 < 260 . 545 hay 19920 < 200315
b) 5217 và 11972
ta có : 5217 > 5216 = 12572 > 11972
Vì 5217 > 5216 hoặc 12572 > 11972
nên 5217 > 11972
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a,
15^12=(3*5)^12=3^12*5^12
81^3*125^5=(3^4)^3*(5^3)^5=3^12*5^15
Vì 12<15 suy ra 5^12<5^15
Suy ra 3^12*5^12<3^12*5^15
\(a.81^3.125^5=\left(3^4\right)^3.\left(5^3\right)^5=3^{12}.5^{15}=3^{12}.5^{12}.5^3=\left(3.5\right)^{12}.5^3=15^{12}.5^3>15^{12}\)
\(b.4^{20}.81^{12}=\left(2^2\right)^{20}.\left(9^2\right)^{12}=2^{40}.9^{24}=2^{20}.2^{20}.9^{20}.9^4=\left(2.9\right)^{20}.2^{20}.9^4=18^{20}.2^{20}.9^4>18^{20}\)
\(c.73^{75}=\left(73^3\right)^{25}=389017^{25}\)
\(107^{50}=107^{2.50}=\left(107^2\right)^{25}=11449^{25}\)
Vì \(389017^{25}>11449^{25}\Rightarrow73^{75}>107^{50}\)
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+ Ta có \(199^{20}< 216^{20}=\left(6^3\right)^{20}=6^{60}\)
+ Ta có \(2003^{15}>1296^{15}=\left(6^4\right)^{15}=6^{60}\)
=> \(199^{20}< 2003^{15}\)
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a) 2003^15 > 2000^15 = (2.10^3)^15 = 2^15.10^45
199^20 < 200^20 = (2.10^2)^20 = 2^20.10^40 =2^15.2^5.10^40 <2^15.10^40.100 =2^15.10^42
Vậy 199^20 < 2003^15
b) 3^99 > 11^21
vì
3^99 = (3³³)³
11^21 = (11^7)³
Còn số mũ giờ so sánh 3³³ và 11^7
3³³ = (3^4)^7 * 3^5
mà 3^4 > 11
==> 3^99 > 11^21
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