If the quantity 2^2+ 2^4 + 2^6 is written as (a + b)(a – b), in which both a and b are integers, which of the following could be the value of b?  Choose the correct choice from the following answers:
A) 12
B) 9
C) 4
D) 2
E) 5
(a+b)(a-b) = a^2 - b^2   2^2+ 2^4 + 2^6 = 2^2 (1+2^2+2^4)   if the above expression is solved even then every term of the expression will remain a multiple of 2^2 which is out of parenthesis   hence, b must be a multiple of 2^2 i.e. 4   Answer: option 4
<result>C</result>
If the quantity 2^2+ 2^4 + 2^6 is written as (a + b)(a – b), in which both a and b are integers, which of the following could be the value of b?