document.write( "Question 322575: Find the center of a circle with the equation x2 + y2 + 2x + 4y – 9 = 0. \n" ); document.write( "

Algebra.Com's Answer #230920 by Fombitz(32388) $\"\"$ $\"About$

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Complete the square in x and y,
\n" ); document.write( " $\"x%5E2+%2B+y%5E2+%2B+2x+%2B+4y-9=0\"$
\n" ); document.write( " $\"%28x%5E2%2B2x%2B1%29%2B%28y%5E2%2B4y%2B4%29-9=1%2B4\"$
\n" ); document.write( " $\"%28x%2B1%29%5E2%2B%28y%2B2%29%5E2=14\"$
\n" ); document.write( "Compare to the general equation of a circle centered at (h,k) with radius R,
\n" ); document.write( " $\"%28x-h%29%5E2%2B%28y-k%29%5E2=R%5E2\"$
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\n" ); document.write( "(h,k)=(-1,-2)\r
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