Check whether the following is quadratic equation :

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

Given,

Equation : (x - 2)(x + 1) = (x - 1)(x + 3)

⇒ x² + x - 2x - 2 = x² + 3x - x - 3

⇒ x² - x - 2 = x² + 2x - 3

⇒ x² - x² = 2x + x - 3 + 2

⇒ 3x - 1 = 0.

The above equation is not of the form ax² + bx + c = 0.

Hence, the above equation is not a quadratic equation.