Question 340182
Complete the square in {{{x}}} and {{{y}}}.
{{{x^2+y^2+4x+2y-20=0}}} 
{{{x^2+4x+y^2+2y-20=0}}}
{{{x^2+4x+4+y^2+2y+1-20=4+1}}}
{{{(x+2)^2+(y+1)^2=25}}}
Compare to the equation of a circle centered at ({{{h}}},{{{k}}}) with radius {{{R}}}.
{{{(x-h)^2+(y-k)^2=R^2}}}