ArunangsuSahu wrote:x not equal to 0. is xy>1?
(1) x>1
(2)1/x<y
For xy>1 , we know that both x and y should either be positive or negative.
St.1 x>1, nothing about y. Insufficient.
St.2 1/x<y, we don't know whether x is positive or negative, so we can't determine because we cannot multiply both sides of the inequality without knowing the sign. If x is positive then it will be 1<xy we don't have to flip the sign if we multiply both sides of the inequality by x. But if x is negative, we have to flip the sign of inequality and it will be 1>xy by multiplying both sides by -x.
Taking both, we know from St.1 that x>1, that is x is positive, so from St.2 if we multiply both sides of the inequality by x we get 1<xy or xy>1. Sufficient.
Ans. C
