document.write( "Question 266969: This is a three part question. I wasn't too sure where to post it, so I posted the question here.\r
\n" ); document.write( "\n" ); document.write( "Given the equation of the circle, label the center and radius of the circle.
\n" ); document.write( "A) X^2 + 2x + y^2 + 10y - 23 = 0\r
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\n" ); document.write( "\n" ); document.write( "C) X^2 + 10X + y^2 - 11 = 0
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Algebra.Com's Answer #196044 by Edwin McCravy(20056)\"\" \"About 
You can put this solution on YOUR website!
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document.write( "You must get these in the standard form\r\n" );
document.write( "for a circle\r\n" );
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document.write( "\"%28x-h%29%5E2%2B%28y-k%29%5E2=r%5E2\"\r\n" );
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document.write( "Then the center is (h,k) and the radius is r.\r\n" );
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document.write( "A)  \r\n" );
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document.write( "\"x%5E2+%2B+2x+%2B+y%5E2+%2B+10y+-+23+=+0\"\r\n" );
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document.write( "Get the constant term on the right by\r\n" );
document.write( "adding \"23\" to both sides:\r\n" );
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document.write( "\"x%5E2+%2B+2x+%2B+y%5E2+%2B+10y+=+23+\"\r\n" );
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document.write( "Multiply the coefficient of \"%22%22%2B2x\",\r\n" );
document.write( "which is \"2\" by \"1%2F2\", getting\r\n" );
document.write( "\"2%2A%281%2F2%29=1\". Then square \"1\",\r\n" );
document.write( "getting \"1%5E2=1\" and add\"%22%22%2B1\" to\r\n" );
document.write( "both sides, putting it right after the\r\n" );
document.write( "\"%22%22%2B2x\" on the left:\r\n" );
document.write( "\r\n" );
document.write( "\"x%5E2+%2B+2x+%2B+1+%2B+y%5E2+%2B+10y+=+23%2B1+\"\r\n" );
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document.write( "Factor the first three terms on the left,\r\n" );
document.write( "and combine the numbers on the right\r\n" );
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document.write( "\"%28x%2B1%29%28x%2B1%29+%2B+y%5E2+%2B+10y+=+24+\"\r\n" );
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document.write( "And write \"%28x%2B1%29%28x%2B1%29\" as \"%28x%2B1%29%5E2\"\r\n" );
document.write( "\r\n" );
document.write( "\"%28x%2B1%29%5E2+%2B+y%5E2+%2B+10y+=+24+\"\r\n" );
document.write( "\r\n" );
document.write( "Multiply the coefficient of \"%22%22%2B10y\",\r\n" );
document.write( "which is \"10\" by \"1%2F2\", getting\r\n" );
document.write( "\"10%2A%281%2F2%29=5\".  Then square \"5\",\r\n" );
document.write( "getting \"5%5E2=25\" and add\"%22%22%2B25\" to\r\n" );
document.write( "both sides, putting it right after the\r\n" );
document.write( "\"%22%22%2B10y\" on the left:\r\n" );
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document.write( "\"%28x%2B1%29%5E2+%2B+y%5E2+%2B+10y+%2B25=+24%2B25+\"\r\n" );
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document.write( "Factor the last three terms on the left,\r\n" );
document.write( "and combine the numbers on the right\r\n" );
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document.write( "\"%28x%2B1%29%5E2+%2B+%28y%2B5%29%28y%2B5%29+=+49+\"\r\n" );
document.write( "\r\n" );
document.write( "And write \"%28y%2B5%29%28y%2B5%29\" as \"%28y%2B5%29%5E2\"\r\n" );
document.write( "\r\n" );
document.write( "\"%28x%2B1%29%5E2+%2B+%28y%2B5%29%5E2+=+49+\"\r\n" );
document.write( "\r\n" );
document.write( "and write \"49\" as \"7%5E2\"\r\n" );
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document.write( "\"%28x%2B1%29%5E2+%2B+%28y%2B5%29%5E2+=+7%5E2+\", which we compare to\r\n" );
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document.write( "\"%28x-h%29%5E2+%2B+%28y-k%29%5E2+=+r%5E2+\", and so\r\n" );
document.write( "\r\n" );
document.write( "since \"-h=%22%22%2B1\" then \"h=-1\", and\r\n" );
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document.write( "since \"-k=%22%22%2B5\" then \"k=-5\", and \"r=7\"\r\n" );
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document.write( "so the center is (h,k) = (-1,-5) and the radius is r=7.\r\n" );
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document.write( "B)  \"x%5E2+%2B+4x+%2B+y%5E2+-+12y+=+24\"\r\n" );
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document.write( "Exactly the same way:\r\n" );
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document.write( "The constant term is already on the right,\r\n" );
document.write( "so we don't have to get it over there.\r\n" );
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document.write( "Multiply the coefficient of \"%22%22%2B4x\",\r\n" );
document.write( "which is \"4\" by \"1%2F2\", getting\r\n" );
document.write( "\"4%2A%281%2F2%29=2\". Then square \"2\",\r\n" );
document.write( "getting \"2%5E2=4\" and add\"%22%22%2B4\" to\r\n" );
document.write( "both sides, putting it right after the\r\n" );
document.write( "\"%22%22%2B4x\" on the left:\r\n" );
document.write( "\r\n" );
document.write( "\"x%5E2+%2B+4x+%2B+4+%2B+y%5E2+-+12y+=+24%2B4+\"\r\n" );
document.write( "\r\n" );
document.write( "Factor the first three terms on the left,\r\n" );
document.write( "and combine the numbers on the right\r\n" );
document.write( "\r\n" );
document.write( "\"%28x%2B2%29%28x%2B2%29+%2B+y%5E2+-+12y+=+28+\"\r\n" );
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document.write( "And write \"%28x%2B2%29%28x%2B2%29\" as \"%28x%2B2%29%5E2\"\r\n" );
document.write( "\r\n" );
document.write( "\"%28x%2B2%29%5E2+%2B+y%5E2+-+12y+=+28+\"\r\n" );
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document.write( "Multiply the coefficient of \"-12y\",\r\n" );
document.write( "which is \"-12\" by \"1%2F2\", getting\r\n" );
document.write( "\"-12%2A%281%2F2%29=-6\".  Then square \"-6\",\r\n" );
document.write( "getting \"%28-6%29%5E2=%22%22%2B36\" and add\"%22%22%2B36\" to\r\n" );
document.write( "both sides, putting it right after the\r\n" );
document.write( "\"-12y\" on the left:\r\n" );
document.write( "\r\n" );
document.write( "\"%28x%2B2%29%5E2+%2B+y%5E2+-+12y+%2B36=+28%2B36+\"\r\n" );
document.write( "\r\n" );
document.write( "Factor the last three terms on the left,\r\n" );
document.write( "and combine the numbers on the right\r\n" );
document.write( "\r\n" );
document.write( "\"%28x%2B2%29%5E2+%2B+%28y-6%29%28y-6%29+=+64+\"\r\n" );
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document.write( "And write \"%28y-6%29%28y-6%29\" as \"%28y-6%29%5E2\"\r\n" );
document.write( "\r\n" );
document.write( "\"%28x%2B2%29%5E2+%2B+%28y-6%29%5E2+=+64+\"\r\n" );
document.write( "\r\n" );
document.write( "and write \"64\" as \"8%5E2\"\r\n" );
document.write( "\r\n" );
document.write( "\"%28x%2B2%29%5E2+%2B+%28y-6%29%5E2+=+8%5E2+\", which we compare to\r\n" );
document.write( "\r\n" );
document.write( "\"%28x-h%29%5E2+%2B+%28y-k%29%5E2+=+r%5E2+\", and so\r\n" );
document.write( "\r\n" );
document.write( "since \"-h=%22%22%2B2\" then \"h=-2\", and\r\n" );
document.write( "\r\n" );
document.write( "since \"-k=%22%22-6\" then \"k=6\", and \"r=8\"\r\n" );
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document.write( "so the center is (h,k) = (-2,6) and the radius is r=8.\r\n" );
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document.write( "C) \"x%5E2+%2B+10x+%2B+y%5E2+-+11+=+0\"\r\n" );
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document.write( "This is just like the other except it'e a little\r\n" );
document.write( "easier because we don't have to complete the square \r\n" );
document.write( "of y because there is no term in y, so we do something \r\n" );
document.write( "else there. But we begin the same way:\r\n" );
document.write( "\r\n" );
document.write( "\"x%5E2+%2B+10x+%2B+y%5E2+-+11+=+0\"\r\n" );
document.write( "\r\n" );
document.write( "Get the constant term on the right by\r\n" );
document.write( "adding \"11\" to both sides:\r\n" );
document.write( "\r\n" );
document.write( "\"x%5E2+%2B+10x+%2B+y%5E2+=+11+\"\r\n" );
document.write( "\r\n" );
document.write( "Multiply the coefficient of \"%22%22%2B10x\",\r\n" );
document.write( "which is \"10\" by \"1%2F2\", getting\r\n" );
document.write( "\"10%2A%281%2F2%29=5\". Then square \"5\",\r\n" );
document.write( "getting \"5%5E2=25\" and add\"%22%22%2B25\" to\r\n" );
document.write( "both sides, putting it right after the\r\n" );
document.write( "\"%22%22%2B10x\" on the left:\r\n" );
document.write( "\r\n" );
document.write( "\"x%5E2+%2B+10x+%2B+25+%2B+y%5E2++=+11%2B25+\"\r\n" );
document.write( "\r\n" );
document.write( "Factor the first three terms on the left,\r\n" );
document.write( "and combine the numbers on the right\r\n" );
document.write( "\r\n" );
document.write( "\"%28x%2B5%29%28x%2B5%29+%2B+y%5E2+=+36+\"\r\n" );
document.write( "\r\n" );
document.write( "And write \"%28x%2B5%29%28x%2B5%29\" as \"%28x%2B5%29%5E2\"\r\n" );
document.write( "\r\n" );
document.write( "\"%28x%2B5%29%5E2+%2B+y%5E2+=+36+\"\r\n" );
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document.write( "Now the only thing we have to do is write the\r\n" );
document.write( "term \"y%5E2\" as \"%28y-0%29%5E2\"\r\n" );
document.write( "\r\n" );
document.write( "\"%28x%2B5%29%5E2+%2B+%28y-0%29%5E2+=+36+\" \r\n" );
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document.write( "Then write the 36 on the right as \"6%5E2\"\r\n" );
document.write( "\r\n" );
document.write( "\"%28x%2B5%29%5E2+%2B+%28y-0%29%5E2+=+6%5E2+\", which we compare to\r\n" );
document.write( "\r\n" );
document.write( "\"%28x-h%29%5E2+%2B+%28y-k%29%5E2+=+r%5E2+\", and so\r\n" );
document.write( "\r\n" );
document.write( "since \"-h=%22%22%2B5\" then \"h=-5\", and\r\n" );
document.write( "\r\n" );
document.write( "since \"-k=%22%220\" then \"k=0\", and \"r=6\"\r\n" );
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document.write( "so the center is (h,k) = (5,0) and the radius is r=6.\r\n" );
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document.write( "Now be sure to learn how to do this by practicing on\r\n" );
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document.write( "some other problems like these, because even though I\r\n" );
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document.write( "can do your homework for you, I can't pass your tests\r\n" );
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document.write( "that you take in class for you, and your homework won't \r\n" );
document.write( "\r\n" );
document.write( "do you any good if you flunk the tests, because your \r\n" );
document.write( "\r\n" );
document.write( "teacher will then know you just got somebody to do your \r\n" );
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document.write( "homework for you.\r\n" );
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document.write( "Edwin
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