A.\(x = 2\)
B.\(x = 3\)
C.\(x = \dfrac{1}{2}\)
D.\(x = \dfrac{1}{3}\)

A.\(\left( { - \infty ;2} \right)\)
B.\(\left( {2; + \infty } \right)\)
C.\(\left( { - \infty ;2} \right]\)
D.\(\left[ {2; + \infty } \right)\)

A.\(180{a^3}\)
B.\(20{a^3}\)
C.\(60{a^3}\)
D.\(10{a^3}\)

A.\(24\pi {a^3}\)
B.\(12\pi {a^3}\)
C.\(4\pi {a^3}\)
D.\(36\pi {a^3}\)

A.\(\overrightarrow {{u_2}}  = \left( {0;3; - 1} \right)\)
B.\(\overrightarrow {{u_3}}  = \left( {1; - 3; - 1} \right)\)
C.\(\overrightarrow {{u_4}}  = \left( {1;2;5} \right)\)
D.\(\overrightarrow {{u_1}}  = \left( {1;3; - 1} \right)\)

A.\(y = 0\)
B.\(x = 0\)
C.\(y - z = 0\)
D.\(z = 0\)

A.\({u_3} = 18\)
B.\({u_3} = 5\)
C.\({u_3} = 6\)
D.\({u_3} = 8\)

A.\(2\pi R\)
B.\(\pi {R^2}\)
C.\(4\pi {R^2}\)
D.\(2\pi {R^2}\)

A.\(x = 3\)
B.\(x = 4\)
C.\(x = 1\)
D.\(x = 2\)

A.Na-va.
B.Đà Lát đờ Tát-xi-nhi.
C.Đờ Ca-xtơ-ri.
D.Bô-la-e.