The correct option is A |x|+|y|
Given: Two real numbers x & y such that xy≥0.
From the triangle inequality:
|x+y|≤|x|+|y|
Case 1: x,y≥0
⇒|x|=x,|y|=y⇒|x+y|=x+y=|x|+|y|
Case 2: x,y≤0
⇒|x|=−x,|y|=−y⇒|x+y|=−(x+y)=−x−y=|x|+|y|⇒|x+y|=|x|+|y|
Thus, we get: |x+y|=|x|+|y| ∀ xy≥0