Question

Prove the identity (a+b) whole square - (a-b) whole square =4ab with paper. Cutting and pasting

Answer 1

(a + b)² - (a - b)² = 4ab. (Proved)

Step-by-step explanation:

(a + b)² - (a - b)² = 4ab

L.H.S = (a + b)² - (a - b)²

         = a² + 2ab + b² - (a² - 2ab + b²)

         = a² + 2ab + b² - a² + 2ab - b²

         = 2ab + 2ab

         = 4ab

         = R.H.S

Hence, (a + b)² - (a - b)² = 4ab. (Proved)