gmat q

[smallsorrow]

a b = a + b + ab
which of the statements is true?
I. a b = b a
II. a 0 = a
III. (a b) c = a (b c)

oa follows

[stop@800]

All the three are true.

The operation shows that it will be commutative and associative.

You can verify the same by expanding also.

III will come out to be
a+b+c+ab+bc+ca+abc

[smallsorrow]

Thats correct.
I just could not figure out III.
c was confusing me....