Is this expression multiplicative? Justify your answer.
f(n)=1, n>1. Factor n into a product of primes,n=p1^k1*
then set f(n)= (-1)^k1+k2+...+kr.
Yes it is.
We need to show f(n)f(m)=f(nm)
Given two integers n and m, suppose n=p1^k1*p2^k2*...*pr^kr,
It is determined whether or not an expression is multiplicative.