Thanks...but I cannot see the proves...
and , for
I didn't know...
Using the identity
we see that
The second factor cannot be zero. Hence, .
Because and are integers, must be an integer.
Jhevon has suggest twice now that you prove the contrapositive: tha tif a does NOT divide b, then does not divide . Why have you not even tried that?
If a does not divide b then b= ma+ k for some k greater than 0 and less than a. . Can you prove that is not a multiple of ?