Question 891632
y^2=1-x^2
x-2y=4


Your system, {{{system(y^2=1-x^2,x-2y=4)}}}


{{{x=2y+4}}};

{{{y^2=1-(2y+4)^2}}}
{{{y^2=1-4y^2+16y+16}}}----MISTAKE HERE!
{{{y^2=1-(4y^2+16y+16)}}}----FIXED MISTAKE!
{{{y^2=1-4y^2-16y-16}}}
{{{0=1-5y^2-16y-16}}}
{{{-5y^2-16y-15=0}}}
{{{highlight(5y^2+16y+15=0)}}}
Discriminant, {{{16^2-4*5*15=256-300=highlight(-44<0)}}}
-
NO REAL SOLUTION BECAUSE DISCRIMINANT IS NEGATIVE.


(EDIT:     Fixed Mistake)