For how many natural numbers x, is the expression: (x ² + 2x + 3) divisible by 35 ?

(In reply to re: Solution by SilverKnight)

Per Brian:
" For any natural number x, (x^2+2x+3) mod 5 is congruent to 2, 3 or 4."

But isn't it 1, 2 or 3?

As it is modular arithmetic, it need be checked only for values of x as 0 through 4, which give 3, 1, 1, 3, 2 respectively.

Posted by Charlie on 2004-01-06 13:18:15