Question 472220
Assuming x,y,z are real numbers not equal to zero, we can say that x^2 is always positive, so x can be either positive or negative. This, however, eliminates choices A and D from always being positive, because if z or y were positive, x could be negative, and vice versa.


We can infer that (y^3)(z^5) is always positive. Hence, y and z must have the same sign. This eliminates choices B and E, because squares are always positive (in this case), and y or z could be negative. This leaves answer choice C as our only option (which must be positive anyway, because y,z have the same sign).