If |x+y|=|x-y|, then x*y must be equal to: Choose one:  A) -1  B) 1  C) 2  D) 0  E) -2
Solution 1: Distance perspective   |x-y| = |x+y| ==&gt; The distance of x and y is equal to the distance of x and -y.   &lt;=======(-y)=======0=======(y)======&gt;   Only 0 is the value that has a distance equal to y and -y.   Solution 2:   |x-y| = |x+y| (square both)   x^2 -2xy + y^2 = x^2 + 2xy + y^2   4xy = 0   xy = 0   Answer: 0
<result>D</result>
If |x+y|=|x-y|, then x*y must be equal to: