Question

plz help me with these questions.

Answer 1

see in 5th

103^2. can be written as (100 + 3)^2

so use formula (a+b)^2 = a^2 + 2ab + b^2


91 × 89 = (90 + 1) (90 - 1)

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

90^2 - 1^2 = 8100 - 1 = 8099