Chứng minh rằng với mọi số nguyên dương n ta luôn có n³ + 5n chia hết cho 6.

A. \(\frac{{a\sqrt 3 }}{4}\);

B. \(\frac{{a\sqrt 2 }}{4}\);

C. \(\frac{{a\sqrt 5 }}{4}\);

D. \(\frac{{a\sqrt 3 }}{3}\).

A. −259;

B. 68;

C. 0;

D. −4.

A. \[{\log _5}\left( {\frac{{1 - \sqrt {21} }}{2}} \right)\];

B. \({\log _5}\left( {\frac{{1 + \sqrt {21} }}{2}} \right)\);

C. 5;

D. \(5\log \left( {\frac{{1 + \sqrt {21} }}{2}} \right)\).

A. 32;

B. 3;

C. 5;

D. 12.

A. (−∞; 1);

B. (0; 1);

C. (0; +∞);

D. (−∞; 0).

A. \(\left[ \begin{array}{l}x = 3\\x = - {\log _5}2\end{array} \right.\);

B. \(\left[ \begin{array}{l}x = 3\\x = {\log _5}2\end{array} \right.\);

C. \(\left[ \begin{array}{l}x = 1\\x = - {\log _5}2\end{array} \right.\);

D. \(\left[ \begin{array}{l}x = 1\\x = {\log _5}2\end{array} \right.\).