So I know how to find the $\delta$ in $f(x)$ that can be factored into a degree of $1$, or I can solve it by solving $L + \epsilon = f(x) $ then finding the distance from $a$. But how do I find the delta analytically for an $f(x)$ for example a degree $2$.
Example: $f(x) = x^2$; $a =3$; $L = 9$; $\epsilon = 0.5$ $$ 0 < |x+3|<\delta $$ $$ |x^2-9| < 0.5 $$ $$ |x+3| |x-3| < 0.5$$ I get stuck at this part when solving the epsilon side.
$$ |x+3| |x-3| < 0.5$$ I can't factor $|x+3|$ like in functions of degree $1$. Can someone please explain?