if |x| - |y| = |x+y| and xy not equal zero , which of the following must be true ?
a) x-y> 0
b) x-y< 0
c) x+y> 0
d) xy> 0
e) xy< 0
need to know whether there is a rule i am missing or a startegy to solve this one.
answer is E
Thanks
Number properties
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- PussInBoots
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I tried all the possible outcomes for this equation.
There are 8 different combinations of positive and negative values of |x|-|y|=|x+y|
You only get two that are not zeros.
x+y=-x-y => xy=-1
-x-y=x+y => xy=-1
Therefore: xy<0 (E)
But this way takes too long, maybe someone can show a quicker way of solving this kind of problem.
There are 8 different combinations of positive and negative values of |x|-|y|=|x+y|
You only get two that are not zeros.
x+y=-x-y => xy=-1
-x-y=x+y => xy=-1
Therefore: xy<0 (E)
But this way takes too long, maybe someone can show a quicker way of solving this kind of problem.
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Need some help on this question.. experts pls helpPedros wrote:if |x| - |y| = |x+y| and xy not equal zero , which of the following must be true ?
a) x-y> 0
b) x-y< 0
c) x+y> 0
d) xy> 0
e) xy< 0
need to know whether there is a rule i am missing or a startegy to solve this one.
answer is E
Thanks
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IMO E.Pedros wrote:if |x| - |y| = |x+y| and xy not equal zero , which of the following must be true ?
a) x-y> 0
b) x-y< 0
c) x+y> 0
d) xy> 0
e) xy< 0
need to know whether there is a rule i am missing or a startegy to solve this one.
answer is E
Thanks
I have got the answer by substituting numbers for X and Y
Substitute X = 5 and Y = -2, works -I
Substitute X = 2 and Y = 5, NO
Substitute X = -2, Y = 5, NO
Substitute X = -5, Y = 2, WORKS
For |X| - |Y| = |X-Y| and XY nt equal to 0, |X| should be higher than |Y|.
OF all the answer choices, E only satisfies the condition.
Hope it helps.
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