Bài tập 2.21 trang 109 SBT Toán 12

A. \(\displaystyle {\log _2}3\)                         

B. \(\displaystyle \ln \sqrt e \)  

C. \(\displaystyle \lg 2,5\)                       

D. \(\displaystyle {\log _3}0,3\)  

A. \(\displaystyle {\log _{\frac{2}{e}}}1,25\)                     

B. \(\displaystyle {\log _{\frac{1}{3}}}0,25\)   

C. \(\displaystyle \ln \frac{1}{{{e^2}}}\)                           

D. \(\displaystyle {\log _{\frac{1}{e}}}3\)   

A. \(\displaystyle 81\)                   

B. \(\displaystyle 9\)  

C. \(\displaystyle \frac{1}{3}\)                   

D. \(\displaystyle \frac{1}{{27}}\)  

A. \(\displaystyle 2\)                   

B. \(\displaystyle 4\)  

C. \(\displaystyle \frac{1}{3}\)                 

D. \(\displaystyle \frac{1}{2}\)   

A. \(\displaystyle 1\)                 

B. \(\displaystyle  - 1\)   

C. \(\displaystyle \frac{1}{e}\)               

D. \(\displaystyle  - \frac{1}{e}\)  

A. \(\displaystyle 2\)             

B. \(\displaystyle  - 2\)   

C. \(\displaystyle \frac{1}{2}\)           

D. \(\displaystyle  - \frac{1}{2}\)   

A. \(\displaystyle{\log _3}\frac{6}{5} < {\log _3}\frac{5}{6}\)

B. \(\displaystyle{\log _{\frac{1}{3}}}17 > {\log _{\frac{1}{3}}}9\)

C. \(\displaystyle{\log _{\frac{1}{2}}}e < {\log _{\frac{1}{2}}}\pi \)

D. \(\displaystyle{\log _2}\frac{{\sqrt 5 }}{2} > {\log _2}\frac{{\sqrt 3 }}{2}\)

Cho \(\displaystyle a = {\log _2}3,b = {\log _3}5,c = {\log _7}2\). Hãy tính \(\displaystyle{\log _{140}}63\) theo \(\displaystyle a,b,c\).

Cho \(\displaystyle a = {\log _3}15,b = {\log _3}10\). Hãy tính \(\displaystyle{\log _{\sqrt 3 }}50\)  theo \(\displaystyle a\) và \(\displaystyle b\). 

Hãy tìm \(\displaystyle x\), biết: \(\displaystyle{\log _{\frac{1}{2}}}x = \frac{2}{3}{\log _{\frac{1}{2}}}a - \frac{1}{5}{\log _{\frac{1}{2}}}b\)