For the vectors a=2i^−j^+3k^, b=−i^+4j^+2k^ and c=3i^+2j^−5k^:
(i) Calculate (a+b)+c.
(ii) Calculate a+(b+c).
(iii) Compare the answers obtained in (i) and (ii) and state the property verified.
(iv) Compute a+b and b+a, then identify the property demonstrated.