Roots with Multiplicity?

[e(ho0n3]

I'm reading a chapter on recurrence relations and they have a problem with the phrase: ...if r is a root with multiplicity 2. What does it mean for a root to have multiplicity? This is the first time I've heard of this and the book assumes I would know what they mean already.

[Hurkyl]

If f(x) is a polynomial, and a is a root of f, then (x - a) is a factor of f(x).

If (x - a) is a repeated factor, that is (x - a)^k is a factor of f(x), then a is a root with multiplicity k.

[e(ho0n3]

I'd figured it be something like that. Thanks for clearing that up.