neeti2711 wrote:What is the greatest common divisor of positive integers m and n?
(1) m is a prime number
(2) m and n are consecutive integers
Target question:
HWhat is the greatest common divisor (GCD) of m and n?
Statement 1: m is a prime number
There are several pairs of numbers that meet this condition. Here are two:
Case a: m=3 and n=3, in which case
the GCD of m and n is 3
Case b: m=3 and n=4, in which case
the GCD of m and n is 1
Since we cannot answer the
target question with certainty, statement 1 is NOT SUFFICIENT
Statement 2: m and n are consecutive integers
Notice that consecutive integers take the form x and x+1
So, if integer d is a divisor of x (such that d does not equal 1), then d cannot be a divisor of x+1.
In other words, 1 is the only divisor that two consecutive positive integers can have in common. As such, the GCD of any two consecutive positive integers must be 1.
So, if m and n are consecutive integers, then
the GCD of m and n must be 1
Since we can answer the
target question with certainty, statement 2 is SUFFICIENT
Answer =
B
Cheers,
Brent
