Question 911603
Use a substitution.
{{{u=(x+6)/x}}}
.
.
{{{u^2+10u+21=0}}}
{{{(u+7)(u+3)=0}}}
Two "u" solutions:
{{{u+7=0}}}
{{{u=-7}}}
{{{(x+6)/x=-7}}}
{{{x+6=-7x}}
{{{-8x=6}}}
{{{highlight(x=-3/4)}}}
.
.
.
{{{u+3=0}}}
{{{u=-3}}}
{{{(x+6)/x=-3}}}
{{{x+6=-3x}}}
{{{-4x=6}}}
{{{highlight(x=-3/2)}}}