Tìm x biết (2x + 5)2 – (x – 2)2 = 0

1)    (2x + 5)2 – (x – 2)2 = 0

2)    x3 – 2x = 0

3)    x2 – 2x + 1 = 0

4)    x2 – 5x + 6 = 0

5)    x3 + 3x2 + 3x + 1 = 0