Question

Which of the following is a quadratic equation?

Options

• (x² + 1) = (2 – x)² + 3

• x³ – x² = (x – 1)³ 

• 2x² + 3 = (5 + x)(2x – 3)

• None of these  

Answer 1

x³ – x² = (x – 1)³ 

Explanation:

∵ x³ – x² = (x – 1)³ 

⇒ x³ – x² = x³ – 3x² + 3x – 1 

⇒ 2x² – 3x + 1 = 0, which is a quadratic equation