Cho \(\dfrac{1}{a} < \dfrac{1}{b}\) và \(ab > 0\). So sánh \(a\) và \(b\).

\(\left( {1;1} \right) \in S\).

\(\left( {\dfrac{{\sqrt 2 }}{2};0} \right) \in S\).

\(\left( {1; - 2} \right) \notin S\).

\(\left( {1;0} \right) \notin S\).

$\left( {\dfrac{{\sqrt 2 }}{2};1} \right).$

$\left( {\dfrac{{\sqrt 2 }}{2};\dfrac{1}{2}} \right)$

$\left[ {\dfrac{{\sqrt 2 }}{2};1} \right]$

$\left( {\dfrac{{\sqrt 3 }}{2};1} \right)$

$m \le 0$ hoặc $m \ge 28$.

$m < 0$ hoặc $m > 28$.

$0 < m < 28$.

$m > 0$.

\(M = \dfrac{1}{4}.\)

\(M = \dfrac{1}{2}.\)

\(M = 1.\)

\(M = 2.\)

${\rm{D}} = \left[ { - \,4; - \,3} \right] \cup \left[ {2; + \infty } \right).$

\({\rm{D}} = \left( { - \,4; + \infty } \right).\)

\({\rm{D}} = \left( { - \,\infty ; - \,3} \right] \cup \left[ {2; + \,\infty } \right).\)

\({\rm{D}} = \left( { - \,4; - \,3} \right] \cup \left[ {2; + \,\infty } \right).\)