If a and b are positive integers divisible by 6, is 6 the greatest common divisor of a and b?
(1) a = 2b + 6
(2) a = 3b
OA A
(1) a = 2b + 6
(2) a = 3b
OA A
--Anand--
a = 6m
b=6n
GCD of 2b+6,b
GCD of 12n+6,6n
GCD of 6(2n+1),6n
n and 2n+1 will never have a common divisor except 1.
Why?
Because, if (2n+1) is divisible by k, say
then 2n is not divisible by k. Because consecutive numbers will not have a common divisor more than 1.
So, if 2n is not divisible by k, then n is not divisible by k.
Hence the GCD of 6(2n+1),6n is 6.
SUFF
a=3b
let b=6,
the a=18
GCD=6
let b=12,
then a=36,
GCD =12
INSUFF
pick A
