Fistail wrote:
Ferihere wrote:
Fistail wrote:
[quote="Ferihere"]If ☉ denotes a mathematical operation, does
x☉y=y☉x for all x and y?
(1) For all x and y, x☉y = 2(x2 + y2).
(2) For all y, 0☉y = 2 y2
A.
1: x☉y = 2 (x^2 + y^2)
y☉x = 2 (y^2 + x^2) suff..
2: 0☉y = 2y^2 could also equal to 2(0^2 +y^2), 2(0 +y)^2 or 2(y +0)^2.
so x☉y could equal to 2(x^2+y^2) or 2y^2 or 2(x+y)^2 so insuffffff..
answer was not really clear...
I still did not get the concept or logic behind...
1: x☉y = 2 (x^2 + y^2)
y☉x = 2 (y^2 + x^2) suff..
2: 0☉y = 2y^2 = 2(0^2 +y^2) = 2(0 +y)^2 = 2(y +0)^2
if so, x☉y = 2 (x^2+y^2) or 2y^2 or 2(x+y)^2 but they all are not equal. so x☉y is not equal to y☉x for all x and y. so st 2 is insuff.........
therefore, it is A.[/quote]
I dont think we need to go till that far at all .It seems we are drawing references from stmnt 1 . 0☉y could be anything while representing 0 in that not necessarily just 2(0^2 +y^2)
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