Question

19. (3) since, ( (m-n) ) is an even number, therefore ( m ) and ( n ) both are either even or odd. And then ( (m+n) ) is even. Now, ( left(m^{2}-n^{2}right)=(m+n) times(m-n) )
Which is the multiplication of two even numbers and therefore always be divisible by 4

# 19. If m and n are two positive integers and (m,n) is an even number, by which of the following (mt -n') is always divisible? (1) 2 (2) 8 (3) 4 (4) 12

Solution