A.\(\dfrac{1}{3}\)
B.\( - \dfrac{1}{3}\)
C.\(\dfrac{{2\sqrt 2 }}{3}\)
D.\( - \dfrac{{2\sqrt 2 }}{3}\)

A.\(1\)
B.\( - 1\)
C.\( - 2\)
D.\(2\)

A.Đồng bằng sông Hồng, Bắc Trung Bộ.
B.Bắc Trung Bộ, Đông Nam Bộ.
C.Đông Nam Bộ, Đồng bằng sông Cửu Long.
D.Đồng bằng sông Cửu Long, Đồng bằng sông Hồng.

A.\(a < 0,\,\,b > 0,\,\,c > 0,\,\,d > 0\)
B.\(a < 0,\,\,b < 0,\,\,c = 0,\,\,d > 0\)
C.\(a < 0,\,\,b > 0,\,\,c = 0,\,\,d > 0\)
D.\(a > 0,\,\,b < 0,\,\,c > 0,\,\,d > 0\)

A.\(16C_{21}^4\)
B.\( - 16C_{21}^4\)
C.\(8C_{21}^3{x^{12}}\)
D.\( - 8C_{21}^3\)

A.\(10\)
B.\(5\)
C.\(7\)
D.\(8\)

A.\({S_{xq}} = 20\pi \,\,c{m^2}\)
B.\({S_{xq}} = 15\pi \,\,c{m^2}\)
C.\({S_{xq}} = 24\pi \,\,c{m^2}\)
D.\({S_{xq}} = 12\pi \,\,c{m^2}\)

A.\(2x + y + 2z - 2 = 0\)
B.\(2x + 2y + 3z - 5 = 0\)
C.\(4x - y + z + 2 = 0\)
D.\(5x - y + 2z + 1 = 0\)

A.\({\left( {x + 1} \right)^2} + {\left( {y - 3} \right)^2} + {\left( {z + 2} \right)^2} = 9\)
B.\({\left( {x + 1} \right)^2} + {\left( {y - 3} \right)^2} + {\left( {z + 2} \right)^2} = 3\)
C.\({\left( {x - 1} \right)^2} + {\left( {y + 3} \right)^2} + {\left( {z - 2} \right)^2} = 3\)
D.\({\left( {x - 1} \right)^2} + {\left( {y + 3} \right)^2} + {\left( {z - 2} \right)^2} = 9\)

A.\(27\pi \)
B.\(64\pi \)
C.\(32\pi \)
D.\(216\pi \)