Official Solution:Is \(x^3*y^2*z^2 > 0\)? For \(x^3*y^2*z^2 > 0\) to be true, \(x\) must be positive, while \(y\) and \(z\) must be non-zero.
(1) \(xy >0\).
This implies that \(x\) and \(y\) have the same sign. If all variables are positive, then the answer is YES. However, if all variables are negative, then the answer is NO. Not sufficient.
(2) \(xz > 0\).
This implies that \(x\) and \(z\) have the same sign. If all variables are positive, then the answer is YES. However, if all variables are negative, then the answer is NO. Not sufficient.<
(1)+(2) The same logic applies: if all variables are positive, the answer is YES. However, if all variables are negative, the answer is NO. Not sufficient.
Essentially, while we know that \(y\) and \(z\) are non-zero, the sign of \(x\) remains undetermined, preventing us from conclusively answering the question.
Answer: E