Question 469975
x+y=8
xy=8
******
x=8-y
y(8-y)=8
{{{8y-y^2=8}}}
{{{y^2-8y+8=0}}}
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}} 
{{{x = (8 +- sqrt( 64-32 ))/(2) }}} 
{{{x = (8 +- sqrt( 32 ))/(2) }}} 
{{{x = (8 +- 4sqrt( 2 ))/(2) }}} 
{{{x = 2(4 +- 2sqrt( 2 ))/(2) }}}
{{{x = 4 +- 2sqrt( 2 ) }}}  
so the positive would be 
{{{x = 4 + 2sqrt( 2 ) }}}  

PS make sure you copied the problem right