My answer is A.

u just have to know the forumla a^2-b^2 = (a+b)(a-b)..ur done !!!

(2^2-1)(2^2+1) (2^4+1) (2^8+1)

the first two terms are in the form of (a+b)(a-b)

hence can be written as 2^4-1

thus the equation now is

(2^4-1) (2^4+1) (2^8+1)

again the first two terms are in that form
hence can written as 2^8-1

now the equation is
(2^8-1) (2^8+1)

thus its 2^16-1.


please let me know if u still have doubts..

Yep I agree
(a+b)(a-b)=a^2 - b^2 is important, as soon as you see figures which can use this formula, it will help you a lot.

Thank you all very much!! Now it looks easy.

Thank you all very much!! Now it looks easy.