Question

so sánh

63^7 và 16^12

b, 17^14 vaf 31^11

c, 2^67 và 5^21

d, 10^31 và 2^100

Answer 1

\(63^7< 64^7=\left(2^6\right)^7=2^{42};16^{12}=\left(2^4\right)^{12}=2^{48}\Rightarrow63^7< 16^{12}\)

\(17^{14}>16^{14}=\left(2^4\right)^{14}=2^{56};31^{11}< 32^{11}=\left(2^5\right)^{11}=2^{55}\Rightarrow17^{14}>31^{11}\)

\(2^{67}=2^{63}.16=128^9.16;5^{21}=125^7\Rightarrow2^{67}>5^{21}\)

\(2^{100}=1024^{10};10^{30}=1000^{10}\Rightarrow\frac{2^{10}}{10^3}=\frac{128}{125}< \frac{20}{19}< \frac{19}{18}< .....< \frac{11}{10}\Rightarrow\frac{2^{100}}{10^3}=\left(\frac{2^{10}}{10^3}\right)^{10}< \frac{20}{19}.\frac{19}{18}.....\frac{11}{10}=2\Rightarrow2^{100}< 2.10^{30}< 10.10^{30}=10^{31}\)