Archit3110 wrote:

Bunuel wrote:

Given z > 0, is x*z > 0?

(1) xz = 3x

(2) xz = -3x

x*z>0

z>0

2.

xz=-3x

z=-3

given z>0 so x would be -ve value or say -1

so xz <0

IMO B

I have hard time understanding S2.

xz = -3x

xz+3x=0

x(z+3)=0

x=0; z=-3 (this cannot be true since we are given that z>0.)

The above case was true when x = 0.

But if x were negative - say as suggested by archit - (-1), then

xz = -3x

-1 * z = -3 * -1

z = -3

z is still negative. That means x cannot be -1 or any negative value for that matter.

If x were positive - say 1.

1 * z = -3 * 1

z = -3

Is there any other value I can try?

Bunuel, could you please help me understand what is the gap in my understanding!

Thank you!