A.\(30W\)
B.\(18\sqrt 3 {\rm{W}}\)
C.\(40W\)
D.\(9\sqrt 3 {\rm{W}}\)

A.\(0,48\mu m\)
B.\(0,64\mu m\)
C.\(0,54\mu m\)
D.\(0,50\mu m\)

A.24
B.28
C.14
D.18

A.1
B.2
C.4
D.3

A.\(2y' + xy'' =  - \dfrac{1}{{{x^2}}}\)
B.\(y' + xy'' = \dfrac{1}{{{x^2}}}\)
C.\(y' + xy'' =  - \dfrac{1}{{{x^2}}}\)
D.\(2y' + xy'' = \dfrac{1}{{{x^2}}}\)

A.\(V = \dfrac{{\pi {a^3}}}{4}\)
B.\(V = \pi {a^3}\)
C.\(V = \dfrac{{\pi {a^3}}}{6}\)
D.\(V = \dfrac{{\pi {a^3}}}{2}\)

A.\(S = 2\)
B.\(S =  - 2\)
C.\(S = 0\)
D.\(S = 1\)

A.\(l = \dfrac{{\sqrt 5 a}}{2}\)
B.\(l = 2\sqrt 2 a\)
C.\(l = \dfrac{{3a}}{2}\)
D.\(l = 3a\)

A.Điểm N
B.Điểm Q
C.Điểm E
D.Điểm P

A.\(I = 2\int\limits_0^3 {\sqrt u du} \)
B.\(I = \int\limits_1^2 {\sqrt u du} \)
C.\(I = \int\limits_0^3 {\sqrt u du} \)
D.\(I = \dfrac{1}{2}\int\limits_1^2 {\sqrt u du} \)