aj5105 wrote:If x is an integer, is (x^2 + 1)(x + 5) an even number?
1)X is an odd number
2)Each prime factor of x^2 is greater than 7.
Hi,
which is the OA? D?
GPREP problem
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To get an even product, we need at least one of the terms to be even.aj5105 wrote:If x is an integer, is (x^2 + 1)(x + 5) an even number?
1)X is an odd number
2)Each prime factor of x^2 is greater than 7.
(x^2 + 1) will be even whenever x is odd. (x + 5) will be even whenever x is odd.
So, the question really is: Is x odd?
(1) sufficient!
(2) whenever you see primes in DS, think about "2", the only even prime number.
If all the prime factors of x^2 are greater than 7, then 2 is NOT a prime factor of x. Therefore, x is odd: sufficient.
Each of (1) and (2) are sufficient alone: choose (D).
Stuart Kovinsky | Kaplan GMAT Faculty | Toronto
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