A.\(0\)
B.\(1\)
C.\(2\)
D.\(3\)

A.\( - 13\)
B.\(13\)
C.\( - 10\)
D.\(10\)

A.\(1 < n < 2021\)
B.\(0 < n < 1\)
C.\(n > 2021\)
D.\(0 < n < 2021\)

A.\( - 3\)
B.\(1\)
C.\( - 1\)
D.\(2\)

A.\(x = 3\)
B.\(x = 0\)
C.\(x = 1\)
D.\(x =  - 1\)

A.\(2\)
B.\(4\)
C.Vô số
D.\(1\)

A.\(498\)
B.\(462\)
C.\(504\)
D.\(426\)

A.\(2a\)
B.\(\dfrac{{a\sqrt {66} }}{{11}}\)
C.\(\dfrac{{11a}}{6}\)
D.\(\dfrac{{2a\sqrt {33} }}{{11}}\)

A.\(5\)
B.\(7\)
C.\(6\)
D.\(9\)

A.\(\dfrac{{\sqrt 3 }}{4}\)
B.\(\dfrac{{\sqrt 3 }}{3}\)
C.\(\dfrac{{\sqrt 3 }}{6}\)
D.\(\dfrac{{2\sqrt 3 }}{3}\)