Which of the following is not a quadratic equation :

1. 2x² = 3x - 5

2. (2x - 1)(x - 1) = 2x² - 7x + 2

3. (2x - 1)(x + 2) = (x - 1)(x + 1)

4. (x + 1)³ = x³ + 2x + 2