# Let $D$ be the domain of the real valued function $f$ defined by $f(x)=\sqrt{25-x^2}.$Then, write $D$

$\begin{array}{1 1} [-5,5] \\ [5,5] \\ [-5,-5] \\ [5,-5] \end{array}$

Toolbox:
• Since f is a real valued function we find internal for n which gives values for f(x)
Since f is a real valued function
$f(x)=\sqrt {25-x^2}$
$25 -x^2 \geq 0$
$(5^2 -x^2) \geq 0$
$(5-x)(5+x) \geq 0$
$(5-x)and (5+x)$ both positive or $(5-x)\; and\; (5+x)$ both negative
$x \geq -5 \; and \; x \leq 5$
Domain $[-5,5]$
answered Mar 1, 2013 by
edited Mar 30, 2013