WholeLottaLove wrote:
Yes, but why does -2|xy| = 2xy?
and is this example posted by Bunuel...
2. ----y--0------x--: y<0<x --> |x|-|y|=x+y and |x+y|=x+y --> x+y={x+y}. Correct.
How does |x| - |y| = x+y? wouldn't it be x-y?
and is this example posted by Bunuel...
2. ----y--0------x--: y<0<x --> |x|-|y|=x+y and |x+y|=x+y --> x+y={x+y}. Correct.
How does |x| - |y| = x+y? wouldn't it be x-y?
|x|-|y| will always be (x-y) ONLY for non-negative values of BOTH x and y. If even one of them is negative, then |x|-|y| will never (x-y). It will be either -x-y (In case x is negative and y positive) OR x-(-y)-->x+y(x positive and y negative).
When y is negative, as |y| is always a non-negative entity, thus we can't write |y| = y. Thus, we attach a negative sign to 'y' to make the entire term (-y) as positive.
Also, even though (x+y) does look like addition of two numbers, it actually isn't, as y is negative.
It will be easier to understand this concept if you use valid nos.