GMATPREP-integer

Question

Solutions pls

iamcartic · Answer

The expression is even if any one of the two in the brackets is even.
From St1: x is for sure odd hence both the expressions inside the bracket are even = thus sufficient

Frm St2: x is not even since 2 (prime) is not a factor of x2 also implies 2 is not a factor of x. Thus x is odd => the expression is even thus sufficient.

sondenso · Answer

1. suff. No discuss
2. prime factor of x^2 is prime factor of x, and prime factor of x bigger than 7, so x must be odd, so x+5 must be even. Suff

D

ritula · Answer

Can u pls elaborate the second statement?

vd · Answer

IMO D is the clear answer on this one

statement 1, explanation in other posts are pretty clear -- and i second / agree with those explanation

statement 2 is sufficent because (rule all prime numbers with the exception of 2 all are odd numbers)

now for x^2 to have a prime factor greater than 7 wud mean that the number is definately odd (because there can be no number x^2 which will have a prime factor greater than 7 until the number itself is the square of a prime number greater than 7, which always will be odd)
consider 17^2=289,11^2=121

therefore x will be an odd number which u plug in the stem u get even * even = even 
therefore the number is even

hence both statements individually are sufficent

therefore D is the answer

HTH

vivektripathi · Answer

From Stat 1 For all odd values of X, X^2 +1 will even no hence either A or D 
From Stat 2 we not sure of factors other than prime hence this stat alone is not suff
answer should be A

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