## Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

$x=\pm\sqrt{11}$
$f(x)=x^{2}$ $f(x)=11$ --- $x^{2}=11$ According to the principle of square roots: For any real number $k$ and any algebraic expression $X$ : $\text{If }X^{2}=k,\text{ then }X=\sqrt{k}\text{ or }X=-\sqrt{k}$ $x=\pm\sqrt{11}$