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a) \(\sqrt{17}>\sqrt{16}=4\); \(\sqrt{26}>\sqrt{25}=5\) => \(\sqrt{17}+\sqrt{26}+1>4+5+1=10=\sqrt{100}>\sqrt{99}\)
Vậy \(\sqrt{17}+\sqrt{26}+1>\sqrt{99}\)
b) \(\frac{1}{\sqrt{1}}>\frac{1}{\sqrt{100}};\frac{1}{\sqrt{2}}>\frac{1}{\sqrt{100}};...;\frac{1}{\sqrt{99}}>\frac{1}{\sqrt{100}}\)
=> \(\frac{1}{\sqrt{1}}+\frac{1}{\sqrt{2}}+...+\frac{1}{\sqrt{100}}>\frac{1}{\sqrt{100}}+\frac{1}{\sqrt{100}}+...+\frac{1}{\sqrt{100}}=\frac{100}{\sqrt{100}}=10\)
Vậy.....
a)Ta có:\(\sqrt{17}>\sqrt{16}\)
\(\sqrt{26}>\sqrt{25}\)
\(\implies\) \(\sqrt{17}+\sqrt{26}>\sqrt{16}+\sqrt{25}\)
\(\implies\) \(\sqrt{17}+\sqrt{26}+1>\sqrt{16}+\sqrt{25}+1=4+5+1=10\)
Mà \(\sqrt{100}=10\) \(\implies\) \(\sqrt{17}+\sqrt{26}+1>\sqrt{100}\)
Mà \(\sqrt{100}>\sqrt{99}\) \(\implies\) \(\sqrt{17}+\sqrt{26}+1>\sqrt{99}\)
b)Ta có:\(\frac{1}{\sqrt{1}}+\frac{1}{\sqrt{2}}+....+\frac{1}{\sqrt{100}}>\frac{1}{\sqrt{100}}+\frac{1}{\sqrt{100}}+...+\frac{1}{\sqrt{100}}=100.\frac{1}{\sqrt{100}}\)
\(\implies\) \(\frac{1}{\sqrt{1}}+\frac{1}{\sqrt{2}}+....+\frac{1}{\sqrt{100}}>\frac{1}{10}.100=10\)
\(\implies\) \(\frac{1}{\sqrt{1}}+\frac{1}{\sqrt{2}}+....+\frac{1}{\sqrt{100}}>10\left(đpcm\right)\)
Ta có: \(99^{20}=\left(99^2\right)^{10}=9801^{10}\)
Vì \(9801< 9999\)nên \(9801^{10}=9999^{10}\)
Vậy \(99^{20}< 9999^{10}\)
a, 2^27 = 2^3.9 = 8^9
3^18 = 3^2.9 = 9^9
vì 8<9 => 8^9 < 9^9 => 2^27 < 3^18
\(\sqrt{7}+\sqrt{15}<\sqrt{9}+\sqrt{16}=3+4=7\Rightarrow\sqrt{7}+\sqrt{15}<7\)
\(\sqrt{2}+\sqrt{11}<\sqrt{3}+\sqrt{25}=\sqrt{3}+5\Rightarrow\sqrt{2}+\sqrt{11}<\sqrt{3}+5\)
\(\sqrt{17}+\sqrt{26}+1>\sqrt{16}+\sqrt{25}+1=4+5+1=10\Rightarrow\sqrt{17}+\sqrt{26}+1>10\)
\(\sqrt{99}<\sqrt{100}=10\Rightarrow\sqrt{99}<10\)
Nên \(\sqrt{17}+\sqrt{26}+1>10\)
a) Ta thấy số dưới lẫn số mũ của 536 lớn hơn 220 => 536>220
b)Ta có:\(99^{200}=99^{100}.99^{100}\)
\(9999^{100}=\left(99.101\right)^{100}=99^{100}.101^{100}\)
VÌ \(99^{100}.99^{100}< 99^{100}.101^{100}\)
Nên: \(99^{200}< 9999^{100}\)
c)Ta có: \(2^{150}=\left(2^3\right)^{50}=8^{50}\)
\(3^{100}=\left(3^2\right)^{50}=9^{50}\)
Vì \(8^{50}< 9^{50}\)nên : \(2^{150}< 3^{100}\)
d)\(\sqrt{26+2}=\sqrt{28}=5< x< 6\)
\(\sqrt{26}+\sqrt{2}=5< x< 6+1< y< 2\)
=> \(\sqrt{26+2}< \sqrt{26}+\sqrt{2}\)
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