A.\({\log _a}\dfrac{1}{x} = \dfrac{1}{{{{\log }_a}x}}\)     
B.\({\log _a}\left( {xy} \right) = lo{g_a}x + {\log _a}y\)
C.\({\log _a}\dfrac{x}{y} = {\log _a}x - {\log _a}y\)   
D.\({\log _b}a.{\log _a}x = {\log _b}x\)

A.\(\ln x < 1 \Leftrightarrow 0 < x < 1\)   
B.\(\log a > \log b \Leftrightarrow a > b > 0\)
C.\(\ln x > 0 \Leftrightarrow x > 1\)     
D.\(\log a < \log b \Leftrightarrow 0 < a < b\)

A.\( - C_8^1{.2^3}\)  
B.\( - C_8^5{.2^5}\)   
C.\(C_8^3{.2^3}\)   
D.\(C_8^5{.2^5}\)

A.\(\dfrac{{21}}{{16}}\)   
B.\(\dfrac{{21\pi }}{{16}}\)   
C.\(\dfrac{{15}}{{16}}\)    
D.\(\dfrac{{15\pi }}{8}\)

A.6 lần  
B.36 lần   
C.12 lần   
D.18 lần

A.4 cạnh  
B.3 cạnh   
C.6 cạnh   
D.5 cạnh

A.\({\log _a}b\)  
B.\({\log _b}c\)   
C.\({\log _c}d\)   
D.\({\log _d}a\)

A.\(y = {\log _3}{x^2}\)  
B.\(y = \log \left( {{x^3}} \right)\)   
C.\(y = {\left( {\dfrac{e}{4}} \right)^x}\)   
D.\(y = {\left( {\dfrac{2}{5}} \right)^{ - x}}\)

A.0,96.
B.1,92.
C.2,4.
D.2,24.

A.\(\left( {1; - 1; - 2} \right)\)  
B.\(\left( { - 1;1;2} \right)\)   
C.\(\left( {3; - 3;4} \right)\)   
D.\(\left( { - 3;3; - 4} \right)\)