Carcass wrote:
If x,y, and z are three non-zero numbers and \(xy>0\) and \(yz<0\), which of the following must be negative?
A. \(xyz\)
B. \(xyz^2\)
C. \(xy^2z\)
D. \(xy^2z^2\)
E. \(x^2y^2z^2\)
F. \(x^2yz\)
G. \(-(x^2y^2z^2)\)
H. \(x^2yz^2\)
I. \(x(-y)z^2\)
J. \(-(xyz^2)\)
Given: \(xy > 0\) and \(yz < 0\)
We can have two cases;
Case I: when \(x\) is +ve, \(y\) is +ve and \(z\) is -ve
Case II: when \(x\) is -ve, \(y\) is -ve and \(z\) is +ve
A. \(xyz < 0\)
Case I: Yes
Case II: NoB. \(xyz^2 < 0\)
Case I: No
Case II: NoC. \(xy^2z < 0\)
Case I: Yes
Case II: YesD. \(xy^2z^2 < 0\)
Case I: No
Case II: YesE. \(x^2y^2z^2 < 0\)
Case I: No
Case II: NoF. \(x^2yz < 0\)
Case I: Yes
Case II: YesG. \(-(x^2y^2z^2) < 0\)
Case I: Yes
Case II: YesH. \(x^2yz^2 < 0\)
Case I: No
Case II: YesI. \(x(-y)z^2 < 0\)
Case I: Yes
Case II: YesJ. \(-(xyz^2) < 0\)[/quote]
Case I: Yes
Case II: YesHence, option C, F, G, I, and J