document.write( "Question 693439: Find the center and radius of x^2+y^2-x+2y+1=0 \n" ); document.write( "

Algebra.Com's Answer #427422 by pmatei(79) $\"\"$ $\"About$

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This is solved by completing the squares:\r
\n" ); document.write( "\n" ); document.write( " $\"x%5E2%2By%5E2-x%2B2y%2B1=0\"$ \r
\n" ); document.write( "\n" ); document.write( " $\"x%5E2-x+%2B%28y%5E2%2B2y%2B1%29=0\"$ \r
\n" ); document.write( "\n" ); document.write( " $\"x%5E2-2%2A%281%2F2%29%2Ax%2B%281%2F2%29%5E2-%281%2F2%29%5E2%2B%28y%2B1%29%5E2=0\"$ \r
\n" ); document.write( "\n" ); document.write( " $\"%28x-1%2F2%29%5E2%2B%28y%2B1%29%5E2=%281%2F2%29%5E2\"$ \r
\n" ); document.write( "\n" ); document.write( "Compare to $\"%28x-x%5B0%5D%29%5E2%2B%28y-y%5B0%5D%29%5E2=r%5E2\"$ where $\"x%5B0%5D\"$ , $\"y%5B0%5D\"$ are the coordinates of the circle's center and $\"r\"$ is the radius.\r
\n" ); document.write( "\n" ); document.write( "The center of the circle is at $\"x%5B0%5D=1%2F2\"$ , $\"y%5B0%5D=-1\"$ and the radius is $\"r=1%2F2\"$ . \n" ); document.write( "

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