ok, (1,1/2) and (-1/2,-1) are still (x,y)? the values are changing with signs then
that's the reason i posted above
and Yes, with (-1/2;-1) works for both statements, BUT then (1/2;1) doesn't work again
you are changing not only signs but
values too in your example, agree?
cans wrote:pemdas wrote:-1=-1/2+1/2 doesn't satisfy the condition 2x-2y=1
from statement (1) x is greater than y, as x=y+1/2 for the positive signs, and x is less than y for the negative signs.
from statement (2) x/y>0 is true for all non-zero y, when x is greater than y for the positive signs, and x is less than y for the negative signs.
combining both statements we get the same conditions, hence no restriction for x and y as being positive.
it must be
e
cans wrote:Spartacus2000 wrote:My mistake.
The first statement is 2x - 2y = 1.
Sorry about that.
a)2x-2y=1 => x = y + 1/2
x&y can be of any sign. For ex (x,y): (0,-1/2) (1,1/2) (-1/2,-1) and so on....
Insufficient.
b)x/y>0 => x and y are of same sign. Either both are positive or both are negative
Thus insufficient.
a & b together) x= y + 1/2 and x,y have same sign.
still insufficient as (1,1/2) & (-1/2,-1) both satisfy these conditions.
Thus IMO
E
I never used(-1,-1/2) as a point. I was other way round (-1/2,-1)
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