The problem asks the following QC question:
xy>0 and yz<0
Quantity A
xz
Quantity B
0
According to the book the answer is B, however I get answer D and my logic is as fallows:
Since xy>0 then x and y have the same sign, either ++ or --
Since yz<0, then y and z have oppositive signs, either +- or -+.
For xz, from the previous could x be positive (because x can be + or -) and z be also positive (because z can be + or -), and then xz can also be positive: ++ or --? If so, then the answer is D because xz can be less than 0 (negative) or more than 0 (positive), but not equal to 0. Is this right?
Thanks,
-f