Question

How to solve 497*505 using suitable identities

Answer 1

Explanation:

497 = 500 - 3

505 = 500+ 5

(x + a) (x + b) = x² + (a + b) x + ab

x = 500; a = -3 ; b= +5

(500 - 3) ( 500 + 5) = (500)² + (-3 +5)500 + (-3)*5

= 250000+ (2)*500 + (-15)

=250000 + 1000 -15

= 250985