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Ta có:
\(5^{217}>5^{216}\)
Mà: \(5^{216}=5^{3\cdot72}=\left(5^3\right)^{72}=125^{72}\)
Lại có: \(125>119\Rightarrow125^{72}>119^{72}\)
\(\Rightarrow5^{216}>119^{72}\)
\(\Rightarrow5^{217}>119^{72}\)
Ta có:
\(5^{75}=\left(5^5\right)^{15}=3125^{15}\)
\(7^{60}=\left(7^4\right)^{15}=2401^{15}\)
Mà: \(3125^{15}>2401^{15}\)
\(\Rightarrow5^{75}>7^{60}\)
_______________
Ta có:
\(3^{39}< 3^{42}\); \(3^{42}=\left(3^6\right)^7=729^7\)
\(11^{21}=\left(11^3\right)^7=1331^7\)
Mà: \(729^7< 1331^7\)
\(\Rightarrow3^{42}< 11^{21}\)
\(\Rightarrow3^{39}< 11^{21}\)
a) \(5^{75}=\left(5^5\right)^{15}=3125^{15}\)
\(7^{60}=\left(7^4\right)^{15}=2401^{15}\)
mà \(2401^{15}< 3125^{15}\)
\(\Rightarrow5^{75}>7^{60}\)
b) \(3^{39}=\left(3^{13}\right)^3=1594323^3;11^{21}=\left(11^7\right)^3=19487171^3\)
mà \(19487171^3>1594323^3\)
\(\Rightarrow3^{39}< 7^{21}\)
Ta có:
$3^{39}=3^{3\times33}=(3^{3})^{33}=27^{33}>27^{21}$
Mà $11^{21}<27^{21}=>3^{39}>11^{21}$
339 = (313)3
1121 = (117)3
313 = (32)6.3 = 96.3 < 116. 11 = 117
⇒ 313 < 117 ⇒ (313)3 < (117)3
⇒ 339 < 1121
Bài 1:
D = 5 + 52 + 53+...+ 5100
5.D = 52 + 53+...+5 100 + 5101
5D - D = 5101 - 5
4D = 5101 - 5
D = \(\dfrac{5^{101}-5}{4}\)
Bài 2:
So sánh
a, 544 = (2.33)4 = 24.312
2112 = (3.7)12 = 312.712
Vì 24 < 712 nên 544 < 2112
b, 339 và 1121
339 = (313)3
1121 = (117)3
313 = (32)6.3 = 96.3 < 97 < 117
Vậy 339 < 1121
1) \(D=5+5^2+5^3+...+5^{100}\)
\(\Rightarrow D+1=1+5+5^2+5^3+...+5^{100}\)
\(\Rightarrow D+1=\dfrac{5^{100+1}-1}{5-1}\)
\(\Rightarrow D+1=\dfrac{5^{101}-1}{4}\)
\(\Rightarrow D=\dfrac{5^{101}-1}{4}-1=\dfrac{5^{101}-5}{4}=\dfrac{5\left(5^{100}-1\right)}{4}\)
2)
a) \(21^{12}=\left(21^3\right)^4=9261^4>54^4\Rightarrow54^4< 21^{12}\)
b) \(3^{39}< 3^{40}=\left(3^2\right)^{20}=9^{20}< 11^{20}< 11^{21}\)
\(\Rightarrow3^{39}< 11^{21}\)
c) \(201^{60}=\left(201^4\right)^{15}=\text{1632240801}^{15}\)
\(398^{45}=\left(398^3\right)^{15}=\text{63044792}^{15}< \text{1632240801}^{15}\)
\(201^{60}>398^{45}\)
\(201^{60}=\left(201^4\right)^{15}=1944810000^{15}\)
\(398^{45}=\left(398^3\right)^{15}=63044792^{15}\)
Do \(1944810000>63044792\)
\(\Rightarrow1944810000^{15}>63044792^{15}\)
\(\Rightarrow201^{60}>398^{45}\)
Ta có:
\(201^{60}>200^{60};398^{45}< 400^{45}\)
\(200^{60}=\left(2.100\right)^{60}=2^{60}.100^{60}=2^{60}.\left(10^2\right)^{60}\)
\(=2^{60}.10^{120}=2^{60}.10^{30}.10^{90}\)
\(400^{45}=\left(2.100\right)^{45}=2^{45}.100^{45}=2^{45}.\left(10^2\right)^{45}\)
\(=2^{45}.10^{90}\)
Mà \(2^{60}.10^{30}.10^{90}>2^{45}.10^{90}\)
\(\Rightarrow200^{60}>400^{45}\)
\(\Rightarrow201^{60}>200^{60}>400^{45}>398^{45}\)
\(\Rightarrow201^{60}>398^{45}\)
Ta có:
\(\frac{22}{49}>\frac{3}{7}\)
Mà \(\frac{3}{7}>\frac{3}{8}\)
=>\(\frac{22}{49}>\frac{3}{8}\)
Cái này có Phân số trung gian là:\(\frac{21}{49}=\frac{3}{7}\)
\(\frac{37}{195}\)và\(\frac{73}{179}\)
Ta có
\(\frac{37}{195}< \frac{37}{179}< \frac{73}{179}\)
\(\Rightarrow\)\(\frac{37}{195}< \frac{73}{179}\)
Vậy \(\frac{37}{195}< \frac{73}{179}\)
em sử dụng phân số trung gian là 1/4 nhé; 16/63>16/64=1/4 = 5/20>5/22
Ta có:
\(3^{39}< 3^{42}\)
Mà: \(3^{42}=\left(3^2\right)^{21}=9^{21}\)
Lại có: \(9< 11\Rightarrow9^{21}< 11^{21}\)
\(\Rightarrow3^{39}< 11^{21}\)