document.write( "Question 116023: How do I identify this equation as a circle and to specify the center and the radius?\r
\n" ); document.write( "\n" ); document.write( " $\"+x%5E2%2By%5E2-8x%2B4y%2B20=0+\"$ \r
\n" ); document.write( "\n" ); document.write( "I worked on the equation and made it into the (x-h)^2+(y-k)^2=r form:\r
\n" ); document.write( "\n" ); document.write( " $\"+%28x-4%29%5E2%2B%28y%2B2%29%5E2=0+\"$ \r
\n" ); document.write( "\n" ); document.write( "but I don't understand how the radius can be zero. \n" ); document.write( "

Algebra.Com's Answer #84392 by stanbon(75887) $\"\"$ $\"About$

You can put this solution on YOUR website!
x^2+y^2-8x+4y+20=0
\n" ); document.write( "--------
\n" ); document.write( "x^2-8x+16 + y^2+4y+4 = -20 + 16 +4
\n" ); document.write( "(x-4)^2 + (x+2)^2 = 0
\n" ); document.write( "-----------------------
\n" ); document.write( "This is not a circle as you said.
\n" ); document.write( "-----------------------
\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H. \n" ); document.write( "

\n" );