Question

Check whether the following is the quadratic equation: 

(x - 2)(x + 1) = (x - 1)(x + 3)

Answer 1

(x - 2)(x + 1) = (x - 1)(x + 3)

⇒ x² - x - 2 = x² + 2x - 3

⇒ x² - x - 2 - x² - 2x + 3 = 0

⇒ -3x - 1 = 0

Since -3x + 1 is a linear polynomial.

∴ (x - 2)(x + 1) = (x - 1)(x + 3) is not a quadratic equation.