# How do you find the domain of p(x)=x^2-2x+8?

The domain of a function is basically all the values that $x$ can take.
In a polynomial function like yours, $x$ can be any real numbers, so the domain is :
$D = \mathbb{R}$.
If your function was something like $p \left(x\right) = \frac{1}{x}$, you would make sure that zero is excluded since you can't divide by zero :
$D = \mathbb{R} - \left\{0\right\}$ or D = ]-oo,0[ uu ]0, +oo[.