DS GMAP Prep2- Numbers
OA- A
I got the Answer by Inserting the numbers. Can you please clarify the Logic by Maths, specially how to reject (2)??
Hi Rajesh,
The question here is ‘Is x a multiple of y’, this question can be rephrased as ‘Is x/y an integer’.
Statement 1 : 3y^2 + 7y = x
Factoring out y we get y(3y +7) = x —–> 3y + 7 = x/y. Since y is an integer then 3y + 7 will also be an integer. Sufficient.
Statement 2 : x^2 – x is a multiple of y
This can be rewritten as (x^2 – x)/y is an integer.
Factoring out x in the numerator we get x(x – 1)/y = integer. Since x is an integer, x – 1 will also be an integer and x/y = integer/integer.
Now an integer/integer may be an integer or may not be an integer. Insufficient.
OA : A