Tìm các hệ số a, b để:\[{\rm{f(x) = }}\frac{{\rm{a}}}{{{\rm{x + 2}}}}{\rm{ + }}\frac{{\rm{b}}}{{{\rm{x + 6}}}}\]

A. \[[ - 1; + \infty )\]

B. \[(1; + \infty )\]

C. \[[\frac{{ - 1}}{3}; + \infty )\]

D. \[( - 1; + \infty )\]

A. \[\sqrt 3 + \frac{{\rm{\pi }}}{{\rm{6}}}\]

B. \[\sqrt 3 - \frac{{\rm{\pi }}}{{\rm{6}}}\]

C. \[\frac{{{\rm{5\pi }}}}{{\rm{6}}} - \sqrt 3 \]

D. \[{\rm{\pi }} - 2\]

A. \[{\rm{A}} = \left( {\begin{array}{*{20}{c}}{\frac{1}{{\sqrt 3 }}}&0&{\frac{2}{{\sqrt 6 }}}\\{\frac{1}{{\sqrt 3 }}}&{\frac{1}{{\sqrt 2 }}}&{\frac{{ - 1}}{{\sqrt 6 }}}\\{\frac{{ - 1}}{{\sqrt 3 }}}&{\frac{1}{{\sqrt 2 }}}&{\frac{1}{{\sqrt 6 }}}\end{array}} \right),{{\rm{P}}^{ - 1}}{\rm{AP}} = \left( {\begin{array}{*{20}{c}}3&0&0\\0&5&0\\0&0&9\end{array}} \right)\]

B. \[{\rm{A}} = \left( {\begin{array}{*{20}{c}}{\frac{{ - 2}}{{\sqrt 6 }}}&0&{\frac{1}{{\sqrt 3 }}}\\{\frac{1}{{\sqrt 6 }}}&{\frac{1}{{\sqrt 2 }}}&{\frac{1}{{\sqrt 3 }}}\\{\frac{{ - 1}}{{\sqrt 6 }}}&{\frac{{ - 1}}{{\sqrt 2 }}}&{\frac{1}{{\sqrt 3 }}}\end{array}} \right),{{\rm{P}}^{ - 1}}{\rm{AP}} = \left( {\begin{array}{*{20}{c}}{ - 2}&0&0\\0&4&0\\0&0&4\end{array}} \right)\]

C. \[{\rm{A}} = \left( {\begin{array}{*{20}{c}}{\frac{1}{{\sqrt 3 }}}&{\frac{1}{{\sqrt 2 }}}&{\frac{1}{{\sqrt 6 }}}\\{\frac{1}{{\sqrt 3 }}}&{\frac{{ - 1}}{{\sqrt 2 }}}&{\frac{1}{{\sqrt 6 }}}\\{\frac{1}{{\sqrt 3 }}}&0&{\frac{{ - 2}}{{\sqrt 6 }}}\end{array}} \right),{{\rm{P}}^{ - 1}}{\rm{AP}} = \left( {\begin{array}{*{20}{c}}0&0&0\\0&3&0\\0&0&3\end{array}} \right)\]

D. \[{\rm{A}} = \left( {\begin{array}{*{20}{c}}{\frac{1}{{\sqrt 6 }}}&{\frac{1}{{\sqrt 2 }}}&{\frac{1}{{\sqrt 3 }}}\\{\frac{1}{{\sqrt 6 }}}&{\frac{{ - 1}}{{\sqrt 2 }}}&{\frac{1}{{\sqrt 3 }}}\\{\frac{{ - 2}}{{\sqrt 6 }}}&0&{\frac{1}{{\sqrt 3 }}}\end{array}} \right),{{\rm{P}}^{ - 1}}{\rm{AP}} = \left( {\begin{array}{*{20}{c}}0&0&0\\0&6&0\\0&0&6\end{array}} \right)\]

A. \[{\rm{I}} = 60\frac{2}{7}\]

B. \[{\rm{I}} = 66\frac{2}{7}\]

C. \[{\rm{I}} = - 60\frac{2}{7}\]

D. \[{\rm{I}} = - 66\frac{2}{7}\]

A. \[\frac{{{\rm{xsin(}}\sqrt {{\rm{1 + }}{{\rm{x}}^{\rm{2}}}} {\rm{)}}}}{{{\rm{(}}\sqrt {{\rm{1 + }}{{\rm{x}}^{\rm{2}}}} {\rm{)}}}}\]

B. \[\frac{{ - {\rm{x}}\sin (\sqrt {1 + {{\rm{x}}^2}} )}}{{(\sqrt {1 + {{\rm{x}}^2}} )}}\]

C. \[\frac{{{\rm{2xsin(}}\sqrt {{\rm{1 + }}{{\rm{x}}^{\rm{2}}}} {\rm{)}}}}{{{\rm{(}}\sqrt {{\rm{1 + }}{{\rm{x}}^{\rm{2}}}} {\rm{)}}}}\]

D. \[\frac{{{\rm{xcos(}}\sqrt {{\rm{1 + }}{{\rm{x}}^{\rm{2}}}} {\rm{)}}}}{{{\rm{(}}\sqrt {{\rm{1 + }}{{\rm{x}}^{\rm{2}}}} {\rm{)}}}}\]

A. p = 1, q = 2

B. p = 2, q = 1

C. p = 1, q = 1

D. p = 0, q = 2

A. \[{\rm{I}} = \frac{{{\rm{2\pi }}}}{{\rm{3}}} - \frac{{\sqrt 3 }}{2}\]

B. \[{\rm{I}} = \frac{{{\rm{2\pi }}}}{{\rm{3}}} + \frac{{\sqrt 3 }}{2}\]

C. \[{\rm{I}} = - \frac{{{\rm{2\pi }}}}{{\rm{3}}} - \frac{{\sqrt 3 }}{2}\]

D. \[{\rm{I}} = - \frac{{{\rm{2\pi }}}}{{\rm{3}}} + \frac{{\sqrt 3 }}{2}\]