document.write( "Question 401886: it might be calculus, but there problem is this...\r
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\n" ); document.write( " x^2 -10x +y^2 + 8y = 28 \n" ); document.write( "
Algebra.Com's Answer #284368 by Edwin McCravy(20060)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "x² - 10x + y² + 8y = 28\r\n" );
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document.write( "Take one-half the -10, which is -5\r\n" );
document.write( "Square -5. Get +25\r\n" );
document.write( "Add +25 to both sides, putting it right after the -10x on the left\r\n" );
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document.write( "x² - 10x + 25 + y² + 8y = 28 + 25\r\n" );
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document.write( "Take one-half the +8, which is +4\r\n" );
document.write( "Square +4. Get +16\r\n" );
document.write( "Add +16 to both sides, putting it right after the 8y on the left\r\n" );
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document.write( "x² - 10x + 25 + y² + 8y + 16 = 28 + 25 + 16\r\n" );
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document.write( "Combine the terms on the right\r\n" );
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document.write( "x² - 10x + 25 + y² + 8y + 16 = 69\r\n" );
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document.write( "Factor the first three terms on the left as (x - 5)(x - 5) and \r\n" );
document.write( "then write it as (x - 5)²\r\n" );
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document.write( "(x - 5)² + y² + 8y + 16 = 69\r\n" );
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document.write( "Factor the last three terms on the left as (y + 4)(y + 4) and \r\n" );
document.write( "then write it as (y + 4)²\r\n" );
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document.write( "(x - 5)² + (y + 4)² = 69\r\n" );
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document.write( "Compare to \r\n" );
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document.write( "(x - h)² + (y - k)² = r²\r\n" );
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document.write( "Then \r\n" );
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document.write( "-h = -5 so h = 5 \r\n" );
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document.write( "-k = +4 so k = -4\r\n" );
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document.write( "So center = (h,k) = (5,-4)\r\n" );
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document.write( "r² = 69, so r = Ö69\r\n" );
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document.write( "Edwin
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