x, y and z nonzero numbers - DS (>700)

[GMAT_ClubMBA]

If x, y and z are nonzero numbers, is ?

(1)

(1)

respuesta: show

C

[Luke]

(1) This expression means that both x and y are >0. In that case, the value of the product depends on the value of z.
If z>0, (y+z) can be >0;<0;=0, depending on the value of z vs value of y. As we don't know anything abut z (only z<>0), this is not sufficient.

(2) This expression means that both y and z are >0. In that case, the product will be positive if X>0 and will be negative if x<0. As we only know x<>0, this is not sufficient.

Together, we know x,y and z are >0, so the product is always positive.

C is the answer

[lox]

|-3 + (- 5)| = |-3| + |-5| :P

[fredurst]

abs(x+y)=abs(x)+abs(y) if x,y are both neg o positive. But the answer to this questions stays the same. C