## Precalculus: Mathematics for Calculus, 7th Edition

$D=\{x|x\in R\}=(-\infty,\infty)$ $R=\{y|y\geq4\}=[4,\infty)$
$f(x)=5x^{2}+4$ This function is not undefined for any value of $x$, so all real numbers form part of the domain of this function: $D=\{x|x\in R\}=(-\infty,\infty)$ We see that if $f(0)=4$ and for every other value of $x$, $f(x)\gt4$, so we can express the range as follows: $R=\{y|y\geq4\}=[4,\infty)$