document.write( "Question 105703: Find the center and the radius of the circle give by \r
\n" ); document.write( "\n" ); document.write( "x^2+8x+y^2+6y-24=0
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Algebra.Com's Answer #76967 by Fombitz(32388)\"\" \"About 
You can put this solution on YOUR website!
The equation of a circle centered at (h,k) with radius, R, is given by:
\n" ); document.write( "\"%28x-h%29%5E2%2B%28y-k%29%5E2=R%5E2\"
\n" ); document.write( "\"%28x%5E2-2hx%2Bh%5E2%29%2B%28y%5E2-2ky%2Bk%5E2%29=R%5E2\"
\n" ); document.write( "\"%28x%5E2-2hx%29%2B%28y%5E2-2ky%29=R%5E2-h%5E2-k%5E2\"
\n" ); document.write( "Let's look at your equation and compare terms.
\n" ); document.write( "\"%28x%5E2%2B8x%29%2B%28y%5E2%2B6y%29-24=0\"
\n" ); document.write( "\"%28x%5E2%2B8x%29%2B%28y%5E2%2B6y%29=24\"
\n" ); document.write( "Comparing,
\n" ); document.write( "1.\"-2hx=8x\"
\n" ); document.write( "2.\"-2ky=6y\"
\n" ); document.write( "3.\"R%5E2-h%5E2-k%5E2=24\"
\n" ); document.write( "From 1,
\n" ); document.write( "1.\"-2hx=8x\"
\n" ); document.write( "\"h=-4\"
\n" ); document.write( "From 2,
\n" ); document.write( "2.\"-2ky=6y\"
\n" ); document.write( "\"k=-3\"
\n" ); document.write( "From 3,
\n" ); document.write( "3.\"R%5E2-h%5E2-k%5E2=24\"
\n" ); document.write( "\"R%5E2-%28-4%29%5E2-%28-3%29%5E2=24\"
\n" ); document.write( "\"R%5E2-16-9=24\"
\n" ); document.write( "\"R%5E2=49\"
\n" ); document.write( "\"R=7\"
\n" ); document.write( "Putting those values back in the first equation,
\n" ); document.write( "\"%28x-h%29%5E2%2B%28y-k%29%5E2=R%5E2\"
\n" ); document.write( "\"%28x-%28-4%29%29%5E2%2B%28y-%28-3%29%29%5E2=49\"
\n" ); document.write( "\"highlight%28%28x%2B4%29%5E2%2B%28y%2B3%29%5E2=49%29\"
\n" ); document.write( "A circle centered at (-4,-3) with a radius of 7.
\n" ); document.write( "Let's verify.
\n" ); document.write( "\"%28x%2B4%29%5E2%2B%28y%2B3%29%5E2=49\"
\n" ); document.write( "\"%28x%5E2%2B8x%2B16%29%2B%28y%5E2%2B6y%2B9%29=49\"
\n" ); document.write( "\"x%5E2%2B8x%2By%5E2%2B6y%2B25-49=49-49\"
\n" ); document.write( "\"x%5E2%2B8x%2By%5E2%2B6y-24=0\"
\n" ); document.write( "Back to your original equation. Good answer.
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