Define x⊕y to be ∣x+y∣ for all real numbers x and y. Which of the following statements is not true?
x⊕y=y⊕x for all x and y
x⊕0=∣x∣ for all x
x⊕(−x)=0 for all x
x⊕y≥0 for all x and y
(x⊕y)⊕z=x⊕(y⊕z) for all x,y,z