a + b + c == 0 (mod n)$and a^5 + b^5 + c^5 == 0 (mod n), abc == 0 (mod n) ;/ 2. Not true! $1+1+1\equiv 0 \mod 3$ $1^5+1^5+1^5\equiv 0 \mod 3$ but $1^3 \not\equiv 0 \mod 3$. 3. Originally Posted by mol How to prove that if: a + b + c == 0 (mod n)$ and a^5 + b^5 + c^5 == 0 (mod n),
This is false: take $a=b=c=2\,,\,\, n = 6$