Question

Which one of the following is not a quadratic equation?

Options

• (x + 2)² = 2(x + 3)

• x² + 3x = (–1)(1 – 3x)²

• x³ – x² + 2x + 1 = (x + 1)³

• (x + 2)(x + 1) = x² + 2x + 3

Answer 1

(x + 2)(x + 1) = x² + 2x + 3

Explanation:

(x + 2)(x + 1) = x² + 2x + 3

So, x² + 3x + 2 = x² + 2x + 3 gives x – 1 = 0

It’s not a quadratic equation.