shobuj wrote:

IF XY NOT EQUAL TO ZERO

WHAT DOES IT MEAN :

XY COULB BE NEGATIVE OR POSITIVE

OR XY MUST BE POSITIVE

PLS DESCRIBE IT ?

If you have any confusal like this, just ask!"IF XY NOT EQUAL TO ZERO", it means that X and Y separately (you can think like that) must be anything except for ZERO. Because Either X or Y equals 0 will make XY equals ZERO.

So:

shobuj wrote:

XY COULB BE NEGATIVE OR POSITIVE

But It is not neccessary that

shobuj wrote:

OR XY MUST BE POSITIVE

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