Câu hỏi:

\(\varnothing \)

\(\{2\}\)

\(\{0;2;5\}\)

\(\{0;1;2\}\)

[2;5]

\([0;2)\)

\([-3;5]\)

\([-3;1)\)

\(\frac{x}{2}-\frac{y}{3}+10<0\)

\(2x-3y+5<0\)

\(x+3{{y}^{2}}-2x+1\le 0\)

\(x-5y-1\ge 0\)

\((0;0)\)

\((1;-3)\)

\((-2;1)\)

\((-5;0)\)

\(\left\{ \begin{align} & x-y<2 \\ & x+{{y}^{2}}>1 \\ \end{align} \right.\)

\(\left\{ \begin{align} & x-y>0 \\ & 2xy<1 \\ \end{align} \right.\)

\(\left\{ \begin{align} & x-2y\le 3 \\ & x+y>-1 \\ \end{align} \right.\)

\(\left\{ \begin{align} & x\le 0 \\ & {{x}^{2}}+{{y}^{2}}<1 \\ \end{align} \right.\)

\(\left\{ \begin{align} & x-2y<-2 \\ & x-2y>3 \\ \end{align} \right.\)

\(\left\{ \begin{align} & x-2y>-2 \\ & x-2y>3 \\ \end{align} \right.\)

\(\left\{ \begin{align} & x-2y>-2 \\ & x-2y<3 \\ \end{align} \right.\)

\(\left\{ \begin{align} & x-2y<-2 \\ & x-2y<3 \\ \end{align} \right.\)

\(\frac{\sqrt{3}}{2}\)

\(\frac{1}{2}\)

\(-\frac{1}{2}\)

\(\frac{\sqrt{2}}{2}\)

\(\tan \alpha <0\)

\(\sin \alpha <0\)

\(\cos \alpha >0\)

\(\cot \alpha >0\)

\({{a}^{2}}={{b}^{2}}+{{c}^{2}}+2bc\cos A\)

\({{a}^{2}}={{b}^{2}}+{{c}^{2}}-2bc\cos B\)

\({{a}^{2}}={{b}^{2}}+{{c}^{2}}+2bc\cos B\)

\({{a}^{2}}={{b}^{2}}+{{c}^{2}}-2bc\cos A\)

\(4+4\sqrt{3}\)

\(2+2\sqrt{3}\)

\(\sqrt{3}-1\)

\(4-4\sqrt{3}\)