document.write( "Question 571239: x^2-x=72 \n" ); document.write( "
Algebra.Com's Answer #368317 by jim_thompson5910(35256)\"\" \"About 
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\n" ); document.write( "\n" ); document.write( "\"x%5E2-x=72\" Start with the given equation.\r
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\n" ); document.write( "\n" ); document.write( "\"x%5E2-x-72=0\" Get every term to the left side.\r
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\n" ); document.write( "\n" ); document.write( "Notice that the quadratic \"x%5E2-x-72\" is in the form of \"Ax%5E2%2BBx%2BC\" where \"A=1\", \"B=-1\", and \"C=-72\"\r
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\n" ); document.write( "\n" ); document.write( "Let's use the quadratic formula to solve for \"x\":\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-B+%2B-+sqrt%28+B%5E2-4AC+%29%29%2F%282A%29\" Start with the quadratic formula\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%28-%28-1%29+%2B-+sqrt%28+%28-1%29%5E2-4%281%29%28-72%29+%29%29%2F%282%281%29%29\" Plug in \"A=1\", \"B=-1\", and \"C=-72\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%281+%2B-+sqrt%28+%28-1%29%5E2-4%281%29%28-72%29+%29%29%2F%282%281%29%29\" Negate \"-1\" to get \"1\". \r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%281+%2B-+sqrt%28+1-4%281%29%28-72%29+%29%29%2F%282%281%29%29\" Square \"-1\" to get \"1\". \r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%281+%2B-+sqrt%28+1--288+%29%29%2F%282%281%29%29\" Multiply \"4%281%29%28-72%29\" to get \"-288\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%281+%2B-+sqrt%28+1%2B288+%29%29%2F%282%281%29%29\" Rewrite \"sqrt%281--288%29\" as \"sqrt%281%2B288%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%281+%2B-+sqrt%28+289+%29%29%2F%282%281%29%29\" Add \"1\" to \"288\" to get \"289\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%281+%2B-+sqrt%28+289+%29%29%2F%282%29\" Multiply \"2\" and \"1\" to get \"2\". \r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%281+%2B-+17%29%2F%282%29\" Take the square root of \"289\" to get \"17\". \r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%281+%2B+17%29%2F%282%29\" or \"x+=+%281+-+17%29%2F%282%29\" Break up the expression. \r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%2818%29%2F%282%29\" or \"x+=++%28-16%29%2F%282%29\" Combine like terms. \r
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\n" ); document.write( "\n" ); document.write( "\"x+=+9\" or \"x+=+-8\" Simplify. \r
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\n" ); document.write( "\n" ); document.write( "So the solutions are \"x+=+9\" or \"x+=+-8\" \r
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