Tuesday, June 26, 2018

elementary number theory - Arithmetic of integers, divisibility

Show that, for $a$ and $b$ integers, it has been $3|a^{2}+b^{2}$ then $3|a$ and $3|b$.



I tried immediately, assuming that 3 divides the sum, then it has to divide separately.

No comments:

Post a Comment

analysis - Injection, making bijection

I have injection $f \colon A \rightarrow B$ and I want to get bijection. Can I just resting codomain to $f(A)$? I know that every function i...