if r@s = rs+r+s, then for what value of s is r@sm equal to r for all values of r?
Apllying the defined operation we get:
find s such that
rsm+r+sm = r
holds for every r
since we know nothing about the "m" part of it, plugging in 1/-1/won't help 'cause m can still be anything and upset the equality.
only 0 works because them the 1st and 3rd terms are always zero and r=r, hich is always true
Answer 0 (C)
"Amicus Plato, sed magic amica veritas"