Question

evaluate 69 × 71 ( by using algebraic method)​​

Answer 1

Solution :-

69 × 71

=> (70 - 1) × (70 + 1)

From algebric formula :-

[ (a - b) (a + b) = a² - b² ]

=> (70)² - (1)²

=> 4900 - 1

=> 4899

Answer 2

69×71=4899

by identity we can write it as - (70-1)(70+1). by using identity (a-b)(a+b)=(a)^2-(b)^2=(70)^2-(1)^2=4900-1=4899