If abc < 0 and bc > 0, which of the following must be positive? Choose one:	A) xy	B) ac	C) (a^2)bc	D) a(b^2)c	E) xy(z^2)
Given that bc is positive and abc is negative, you can say that a MUST be negative. As for b and c either they are both positive or both negative.   Option (C) has a^2 which is positive and bc which is positive. So ((a^2)bc) must be positive.
<result>C</result>
If abc < 0 and bc > 0, which of the following must be positive?