a) a + 2x = a
=> 2x = a - a = 0
=> 2x = 0
=> x = 0
b) a + 2x > a
=> 2x > 0
=> x > 0
c) a + 2x < a
=> 2x < 0
=> x < 0
Vậy,.........
a) a + 2x = a
=> 2x = 0
x = 0
b) a + 2x > a
2x > 0
x > 0
c) a + 2x < a
2x < 0
x < 0
a + 2x = a
2x = a - a
2x = 0
x = 0
a + 2x > a
2x > a - a
2x > 0
x > 0
a + 2x < a
2x < a - a
2x < 0
x < 0