Check whether the following equation is a quadratic equation:
(x + 2)³ = x³ - 4

The correct answer is Yes, this is a quadratic equation

LHS = (x + 2)³ = (x + 2)(x + 2)(x + 2)
= (x² + 4x + 4)(x + 2)
= x³ + 4x² + 4x + 2x² + 8x + 8
= x³ + 6x² + 12x + 8
RHS = x³ - 4
∴ The given equation can be written as x³ + 6x² + 12x + 8 = x³ - 4
⇒ 6x² + 12x + 8 = - 4
⇒ 6x² + 12x + 12 = 0
The above equation is of the form ax² + bx + c = 0
∴ This equation is a quadratic equation