More Finding Zeros of a Polynomial

Hello, all. I have three problems related to finding zeros of a polynomial.

First problem:

I need to find the zeros of the following polynomial so that I can graph it:

$\displaystyle x^4-2x^3-5x^2+8x+4$

Using synthetic division, I found two zeros and so now I have:

$\displaystyle (x+2)(x-2)(x^2-2x-1)$

I'm not sure how to factor $\displaystyle x^2-2x-1$ to find the remaining zeros.

Second problem:

I need to find the zeros of the following polynomial so that I can graph it:

$\displaystyle 2x^3+6x^2+5x+2$

Using synthetic division, I found one zero, so now I have:

$\displaystyle (x+2)(x^2+x+\frac{1}{2})$

I'm pretty sure that $\displaystyle x^2+x+\frac{1}{2}$ can't be factored, so what does this mean for the graph?

Final problem:

I need to find the zeros of the following polynomial so that I can graph it:

$\displaystyle x^4-4x^3-x^2+14x+10$

I used synthetic division to find:

$\displaystyle (x+1)^2(x^2-6x+10)$

Again, it doesn't seem that I can factor any further. What does this mean for the graph?

Thanks again!