valerjo79 wrote:

All,

I am writing as I seem not to be getting the point of this DS question. I have done twice over different days, and always answered the same way without getting the explanation: would you please help? I am missing the point, because to me each statement is sufficient to answer the question, though in different ways (1) even, (2) not even

If x is an integer, is x even?

(1) x(x + 1) is even.

(2) x(x + 2) is even.

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

Both statements TOGETHER are sufficient, but NEITHER one ALONE is sufficient.

EACH statement ALONE is sufficient.

Statements (1) and (2) TOGETHER are NOT sufficient.

Much obliged,

Valerio

Statement 1: x(x+1) is even

it could be that

a) x is even and x+1 is odd b) x is odd and x+1 is even {both even not possible as consecutive numbers)

Thus we cant conclude that x is even. Not sufficient.

Also, you can also deduce it in this way -> x and x+1 are consecutive integers. One has to be odd and one even but you cant say which one is odd.eg. 2*3 and 3*4 both are even.

b) x(x+2) is even

this would mean that a) x is even or b) x+2 is even. {or both are even}

but note, if x+2 is even that means even x is even.

Sufficient.

Ans B it is.

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