document.write( "Question 236187: x^-x=1 what is the solution set{ }?
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Algebra.Com's Answer #173879 by jim_thompson5910(35256)\"\" \"About 
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\n" ); document.write( "\n" ); document.write( "\"x%5E2-x=1\" Start with the given equation.\r
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\n" ); document.write( "\n" ); document.write( "\"x%5E2-x-1=0\" Subtract 1 from both sides.\r
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\n" ); document.write( "\n" ); document.write( "Notice that the quadratic \"x%5E2-x-1\" is in the form of \"Ax%5E2%2BBx%2BC\" where \"A=1\", \"B=-1\", and \"C=-1\"\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%28-1%29+%29%29%2F%282%281%29%29\" Plug in \"A=1\", \"B=-1\", and \"C=-1\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%281+%2B-+sqrt%28+%28-1%29%5E2-4%281%29%28-1%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%28-1%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--4+%29%29%2F%282%281%29%29\" Multiply \"4%281%29%28-1%29\" to get \"-4\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%281+%2B-+sqrt%28+1%2B4+%29%29%2F%282%281%29%29\" Rewrite \"sqrt%281--4%29\" as \"sqrt%281%2B4%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%281+%2B-+sqrt%28+5+%29%29%2F%282%281%29%29\" Add \"1\" to \"4\" to get \"5\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+%281+%2B-+sqrt%28+5+%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%2Bsqrt%285%29%29%2F%282%29\" or \"x+=+%281-sqrt%285%29%29%2F%282%29\" Break up the expression. \r
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\n" ); document.write( "\n" ); document.write( "So the solutions are \"x+=+%281%2Bsqrt%285%29%29%2F%282%29\" or \"x+=+%281-sqrt%285%29%29%2F%282%29\" \r
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\n" ); document.write( "\n" ); document.write( "which approximate to \"x=1.618\" or \"x=-0.618\"
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