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a/ \(63^7< 64^7=\left(4^3\right)^7=4^{21}\)
\(16^{12}=\left(4^2\right)^{12}=4^{24}\)
Suy ra \(63^7< 4^{21}< 4^{24}=16^{12}\)
Vậy \(63^7< 16^{12}\)
\(-\frac{1}{7}\)và \(-\frac{5}{35}\)
Ta có:\(\frac{-5}{35}=\frac{-5:5}{35:5}=\frac{-1}{7}\)
\(\Rightarrow\frac{-1}{7}=\frac{-5}{35}\)
km mk nha@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
ta có \(\frac{-5}{35}\)= \(\frac{-1}{7}\)
suy ra \(\frac{-1}{7}\)= \(\frac{-5}{35}\)
ta có \(-0,6\)= \(\frac{-3}{5}\)=\(\frac{-9}{15}\)
\(\frac{2}{-3}\)= \(\frac{-2}{3}\)= \(\frac{-10}{15}\)
mà \(\frac{-9}{15}\)> \(\frac{-10}{15}\)
suy ra \(-0,6\)> \(\frac{2}{-3}\)
ta có \(-1\frac{3}{4}\)= \(\frac{-7}{4}\)= \(-1,75\)
mà \(1,25\)> \(-1,75\)
suy ra \(-1\frac{3}{4}\)< \(1,25\)
a) Ta có :
\(\hept{\begin{cases}27^{11}=\left(3^3\right)^{11}=3^{33}\\81^8=\left(3^4\right)^8=3^{32}\end{cases}}\)
Vì 333 > 332
=> 2711 > 818
b) Ta có:
\(\hept{\begin{cases}2^{225}=\left(2^3\right)^{75}=8^{75}\\3^{150}=\left(3^2\right)^{75}=9^{75}\end{cases}}\)
Vì 875 < 975
=> 2225 < 3150
Thôi còn lại bn tự làm nốt nha . Nhìn mà nản !!
a) \(\hept{\begin{cases}27^{11}=\left(3^3\right)^{11}=3^{33}\\81^8=\left(3^4\right)^8=3^{32}\end{cases}}\)
333 > 332 => 2711 > 818
b) \(\hept{\begin{cases}2^{225}=\left(2^3\right)^{75}=8^{75}\\3^{150}=\left(3^2\right)^{75}=9^{75}\end{cases}}\)
875 < 975 => 2225 < 3150
c) \(\hept{\begin{cases}2^{500}=\left(2^5\right)^{100}=32^{100}\\5^{200}=\left(5^2\right)^{100}=25^{100}\end{cases}}\)
32100 > 25100 => 2500 > 5200
d) \(\hept{\begin{cases}625^5=\left(5^4\right)^5=5^{20}\\125^7=\left(5^3\right)^7=5^{21}\end{cases}}\)
520 < 521 => 6255 < 1257
e) \(\hept{\begin{cases}5^{100}=\left(5^4\right)^{25}=625^{25}\\8^{75}=\left(8^3\right)^{25}=512^{25}\end{cases}}\)
62525 > 51225 => 5100 > 875
f) \(2^{16}=2^3\cdot2^{13}=8\cdot2^{13}\)
7 < 8 => 7.213 < 8.213 => 7.213 < 216
g) Ta có \(\frac{27^{50}}{240^{30}}=\frac{\left(3^3\right)^{50}}{3^{30}\cdot80^{30}}=\frac{3^{150}}{3^{30}\cdot80^{30}}=\frac{3^{120}}{80^{30}}=\frac{\left(3^4\right)^{30}}{80^{30}}=\frac{81^{30}}{80^{30}}\)
Vì 8130 > 8030 => 8130/8030 > 1 => 2750/24030 > 1 => 2750 > 24030
h) Ta có \(\hept{\begin{cases}63^9< 64^9=\left(2^6\right)^9=2^{54}\left(1\right)\\16^{14}=\left(2^4\right)^{14}=2^{56}< 17^{14}\left(2\right)\end{cases}}\)
Từ (1) và (2) => 639 < 254 < 256 < 1714
=> 639 < 1714
Vì 2 < 3 và 22 < 32 => 222 < 332
3111<3211. Mà 3211=(25)11=255.
=>3111<255.
1714>1614. Mà 1614=(24)14=256.
Mà 255<256=>3111<255<256<1714=>3111<1714.
222 và 322
Vì 2 < 3; 22 < 32 nên 222 < 332
3111 và 1714
3111 = 319 . 312
1714 = 179 . 175
Mà 179 < 319 , 175 > 312 nên 3111 < 1714
a) Ta có : \(31^5< 32^5=\left(2^5\right)^5=2^{25}< 2^{28}=\left(2^4\right)^7=16^7< 17^7\)
\(\Rightarrow31^5< 17^7\)
b) Ta có : \(8^{12}=\left(2^3\right)^{12}=2^{36}>2^{32}=\left(2^4\right)^8=16^8>12^8\)
\(\Rightarrow8^{12}>12^8\)
c) \(A=\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+...+\frac{1}{3^{99}}\)
\(3A=1+\frac{1}{3}+\frac{1}{3^2}+...+\frac{1}{3^{98}}\)
\(3A-A=\left(1+\frac{1}{3}+\frac{1}{3^2}+...+\frac{1}{3^{98}}\right)-\left(\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+...+\frac{1}{3^{99}}\right)\)
\(2A=1-\frac{1}{99}\)
\(A=\frac{1-\frac{1}{99}}{2}< \frac{1}{2}\)
\(\Rightarrow A< \frac{1}{2}\)
a) \(31^5< 34^5=2^5.17^5=32.17^5\)
\(17^7=17^2.17^5=289.17^5\)
\(\Rightarrow31^5< 17^7\)
b) \(12^8< 16^8=\left(2^4\right)^8=2^{32}\)
\(8^{12}=\left(2^3\right)^{12}=2^{36}\)
\(\Rightarrow8^{12}>12^8\)
c) \(A=\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+...+\frac{1}{3^{99}}\)
\(3A=1+\frac{1}{3}+\frac{1}{3^2}+...+\frac{1}{3^{98}}\)
\(\Rightarrow3A-A=1+\left(\frac{1}{3}-\frac{1}{3}\right)+\left(\frac{1}{3^2}-\frac{1}{3^2}\right)+...+\left(\frac{1}{3^{98}}-\frac{1}{3^{98}}\right)-\frac{1}{3^{99}}\)
\(\Rightarrow2A=1-\frac{1}{3^{99}}< 1\Rightarrow A< \frac{1}{2}\)
a) \(\frac{17}{30}>\frac{51}{92}\)
b) \(\frac{-45}{47}>\frac{31}{-30}\)
c) \(\frac{22}{67}< \frac{51}{152}\)
d) \(-\frac{17}{39}< -\frac{17}{41};\frac{18}{-39}< -\frac{17}{41}\)
a) có \(\sqrt{2}\) <\(\sqrt{3}\)
5= \(\sqrt{25}\) >\(\sqrt{11}\)
=>\(\sqrt{2}+\sqrt{11}< \sqrt{3}+5\)
b)có \(\sqrt{21}>\sqrt{20}\)
-\(\sqrt{5}\) >-\(\sqrt{6}\)
=>\(\sqrt{21}-\sqrt{5}>\sqrt{20}-\sqrt{6}\)
a) \(63^7\)và \(16^{12}\)
Có \(63^7< 64^7=\left(2^6\right)^7=2^{42}\)
\(16^{12}=\left(2^4\right)^{12}=2^{48}\)
Mà \(2^{42}< 2^{48}\Rightarrow63^7< 64^7< 16^{12}\)=) \(63^7< 16^{12}\)
b) \(17^{14}\)và \(31^{11}\)
Có \(17^{14}>16^{14}=\left(2^4\right)^{14}=2^{56}\)
\(31^{11}< 32^{11}=\left(2^5\right)^{11}=2^{55}\)
Vì \(2^{56}>2^{55}\Rightarrow17^{14}>16^{14}>32^{11}>31^{11}\)
=) \(17^{14}>31^{11}\)
c) \(2^{67}\)và \(5^{21}\)
Có \(5^{21}< 8^{21}=\left(2^3\right)^{21}=2^{63}\)
Vì \(2^{67}>2^{63}\Rightarrow2^{67}>8^{21}>5^{21}\)
=) \(2^{67}>5^{21}\)