Polynomial rest (can i use Mod-command?)

Questions
1

If I want to know a rest polynomial divided by a lower ponomial

Tried

Mod[{ x^3 + 6x^2 + 13x + 9},{x^2+2*x+1}]

that did not work

2

Hi,

what about

PolynomialQuotientRemainder[x^3 + 6 x^2 + 13 x + 9, x^2 + 2*x + 1, x][[2]]

Cheers,
Marco

3

Thanks, it worked!
But what does the [[2]] for?

4

PolynomialQuotientRemainder returns a list with the quotient in the first position and the remainder in the second. You only asked for the remainder, that his why I chose the second entry of that list.

Cheers,

Marco