Re: ISI INTERVIEW PREP

Posted by Preet on Jul 05, 2012; 10:07am
URL: http://discussion-forum.276.s1.nabble.com/ISI-INTERVIEW-PREP-tp7578819p7579120.html

p2 − q2 = (p+q)(p-q) = some prime no. Prime no have only two factors- 1 and the number itself.
now p+q cannot be 1 unless one of the either p or q is zero. Hence, p-q is 1. :)