Question

using suitable identity evaluate 399×401​

Answer 1

Answer:

(400-1)(400+1)=160000-1=159999

by identity a^2-b^2=(a+b)(a-b)

Answer 2

Answer:

(400-1)(400+1)

using identity (a+b)(a-b)=a2-b2

(400)2 - (1)2

1600-1

1599