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

$\{16,256\}$
Substitute $u=x^{1/4},$ $u^{2}-6u+8=0$ ... factor: search for factors of 8 with sum -6... ... we find $-2$ and $-4$ $(u-2)(u-4)=0$ $u=2$ or $u=4$ ... bring back x $x^{1/4}=2 \qquad$or$\qquad x^{1/4}=4$ $x=2^{4} \qquad$or$\qquad x= 4^{4}$ $x=16 \qquad$or$\qquad x= 256$ Solution set = $\{16,256\}$