## Elementary Geometry for College Students (7th Edition)

$x=9, x=-9$
$\frac {x+1}{5}=\frac {16}{x-1}$ Cross Multiply... $(x+1)(x-1)=5(16)$ Simplify by multiplying $x^{2}+1x-1x-1=80$ $x^{2}-1=80$ Add 1 to both sides... $x^{2}=81$ Square root both sides... $x=9, x=-9$