A.\(+\infty\)
B.\(-\infty\)
C.\(0\)
D.Không tồn tại

A.Na.
B.Al.
C.Fe.
D.Be.

A.gardens in Madrid, New York, and Chicago
B.people growing plants on roofs and walls
C.private gardens in the city's unused spaces
D.how to grow your own food in the city

A.\(\left( {x;y} \right) = \left( {\dfrac{{11}}{5};\dfrac{7}{5}} \right)\)
B.\(\left( {x;y} \right) = \left( { - \dfrac{{11}}{5};\dfrac{7}{5}} \right)\)
C.\(\left( {x;y} \right) = \left( {\dfrac{{11}}{5}; - \dfrac{7}{5}} \right)\)
D.\(\left( {x;y} \right) = \left( { - \dfrac{{11}}{5}; - \dfrac{7}{5}} \right)\)

A.\(S = \left\{ {\dfrac{{3 \pm \sqrt 5 }}{2}} \right\}\)
B.\(S = \left\{ {\dfrac{{3 \pm \sqrt 7 }}{2}} \right\}\)
C.\(S = \left\{ {\dfrac{{2 \pm \sqrt 7 }}{2}} \right\}\)
D.\(S = \left\{ {\dfrac{{2 \pm \sqrt 5 }}{2}} \right\}\)

A.\(C =  - 8\sqrt 2 \)
B.\(C =  - 9\sqrt 2 \)
C.\(C =  - 10\sqrt 2 \)
D.\(C =  - 11\sqrt 2 \)

A.\(B = \dfrac{9}{2}\)
B.\(B = \dfrac{{11}}{2}\)
C.\(B = \dfrac{{13}}{2}\)
D.\(B = \dfrac{{15}}{2}\)

A.\(A = 14\sqrt 5  - 15\)
B.\(A = 12\sqrt 5  - 15\)
C.\(A = 10\sqrt 5  - 8\)
D.\(A = 12\sqrt 5  - 8\)

A.\(V = \dfrac{4}{3}\pi {a^3}\)
B.\(V = \dfrac{{32}}{3}\pi {a^3}\)
C.\(V = 4\pi {a^3}\)  
D.\(V = 8\pi {a^3}\)

A.\(S = \dfrac{1}{2}\pi {a^2}\)
B.\(S = 4\pi {a^2}\)
C.\(S = \pi {a^2}\)   
D.\(S = 2\pi {a^2}\)