Question

Using the identity (a + b) (a - b) = a - b², evaluate 49 × 51.​

Answer 1

49 × 51

Using Identity

• (a + b) (a - b) = a - b²

Solution

⇛(50 + 1) (50 - 1)

⇛(50)² - (1)²

⇛2500 - 1

⇛2499

Answer 2

`\\ \sf\longmapsto 49* 51`

`\\ \sf\longmapsto (50-1)(50+1)`

`\\ \sf\longmapsto (50)^2-(1)^2`

`\\ \sf\longmapsto 2500-1`

`\\ \sf\longmapsto 2499`