Well, I've a defined function below to show and share with you guys from a textbook which is used in Math(s):
$f(x) = \frac{3}{2+x^2}$ and notates $f(-x) = f(x)$,
$f: D_f\to R_f$ and $x^2+2 \neq 0$ and $D_f=\mathbb R$ ,
for all $x \in \mathbb R: 0 < f(x) = \frac{3}{2+x^2}\leq 3 / 2, R_f=(0, 3/2]$ and declares $[0, +\infty)$
Could you help me some to analyse and understand this function equation, more particularly, for $D_f=\mathbb R$ definition. What about $x^2+2 \neq 0$ declaring, it seems like there is something missing with that $D_f$'s set assignment...? Any idea, please?
By the way, should a function ever equal a negative value for it's display ($R_f$) set?
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