When 25435438 is divided by 5 the remainder is 3 so 25435438 is a multiple of 5 plus 3 more. That is there is a number n so that
25435438 = 5 n + 3
When kx2+3x+1 divided by (x-2) the remainder is 3 so kx2+3x+1 is a multiple of (x - 2) plus 3 more. That is there is a polynomial p(x) so that
kx2+3x+1 = (x - 2) p(x) + 5
Substitute x = 2.