# Question #156df

##### 1 Answer
Aug 14, 2017

$x \in \left(- \infty , \infty\right)$
$y \in \left(4 , \infty\right)$

#### Explanation:

Given $y = {x}^{2} + 4$
So if we are interested in finding maximum or natural domain of $x$ then $x$ can take any real value as for every real value of $x$ we get a real value of $y$.

But as for any real number, the square of any real number is always non negative and hence
${x}^{2} \ge 0$
$\implies {x}^{2} + 4 \ge 4$
$\therefore y \ge 4$