A.\(\left| {a + b} \right| = \left| a \right| + \left| b \right|\)
B.\(\left| {a + b} \right| \le \left| a \right| + \left| b \right|\)
C.\(\left| {a + b} \right| < \left| a \right| + \left| b \right|\)
D.\(\left| {a + b} \right| > \left| a \right| + \left| b \right|\)

A.\({a^2} + ab + {b^2} > 0\)
B.\(a - b < 0\)
C.\(a + b > 0\)
D.\({a^2} - ab + {b^2} < 0\)

A.\(2\)
B.\(4\)
C.\(0\)
D.\(6\)

A.\(M.m = 0\)
B.\(M.m =  - 25\)
C.\(M.m =  - 10\)
D.\(M.m = 10\)

A.\(\max P = 36 \Leftrightarrow a = \dfrac{1}{6};\,\,b = \dfrac{1}{3};\,\,c = \dfrac{1}{2}\)
B.\(\min P = 36 \Leftrightarrow a = \dfrac{1}{6};\,\,b = \dfrac{1}{3};\,\,c = \dfrac{1}{2}\)
C.\(\max P = 6 \Leftrightarrow a = \dfrac{1}{6};\,\,b = \dfrac{1}{3};\,\,c = \dfrac{1}{2}\)
D.\(\min P = 6 \Leftrightarrow a = \dfrac{1}{6};\,\,b = \dfrac{1}{3};\,\,c = \dfrac{1}{2}\)

A.\(S = 3\)
B.\(S = 4\)
C.\(S = 5\)
D.\(S = 6\)

A.\(\dfrac{a}{b} + \dfrac{b}{a} \ge 2\)
B.\(\dfrac{a}{b} + \dfrac{b}{a} \ge  - 2\)
C.\(\dfrac{a}{b} + \dfrac{b}{a} \le  - 2\)
D.\(\dfrac{a}{b} + \dfrac{b}{a} \le 2\)

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

A.\(16\sqrt 3 \,cm\)
B.\(20\sqrt 3 \,cm\)
C.\(16\,cm\)
D.\(20\,cm\)

A.\(x > y\)
B.\(x < y\)
C.\(x = y\)
D.Không so sánh được