If pqr < 0 and qr > 0, which of the following must be positive?	Choose the correct choice from the following answers:  A) xy  B) xz  C) (p^2)qr  D) p(q^2)r  E) xy(z^2)
Given that qr is positive and pqr is negative, you can say that p MUST be negative. As for q and r either they are both positive or both negative.   Option (C) has p^2 which is positive and qr which is positive. So ((p^2)qr) must be positive.
<result>C</result>
If pqr < 0 and qr > 0, which of the following must be positive?