document.write( "Question 186689: x^-4-3x^-2-4=0 \n" ); document.write( "
Algebra.Com's Answer #139950 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
\"x%5E%28-4%29-3x%5E%28-2%29-4=0\" Start with the given equation.\r
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\n" ); document.write( "\n" ); document.write( "Let \"z=x%5E%28-2%29\". So this means that \"z%5E2=x%5E%28-4%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"z%5E2-3z-4=0\" Replace \"x%5E%28-4%29\" with \"z%5E2\". Replace \"x%5E%28-2%29\" with \"z\"\r
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\n" ); document.write( "\n" ); document.write( "Notice we have a quadratic equation in the form of \"az%5E2%2Bbz%2Bc\" where \"a=1\", \"b=-3\", and \"c=-4\"\r
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\n" ); document.write( "\n" ); document.write( "Let's use the quadratic formula to solve for z\r
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\n" ); document.write( "\n" ); document.write( "\"z+=+%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( "\"z+=+%28-%28-3%29+%2B-+sqrt%28+%28-3%29%5E2-4%281%29%28-4%29+%29%29%2F%282%281%29%29\" Plug in \"a=1\", \"b=-3\", and \"c=-4\"\r
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\n" ); document.write( "\n" ); document.write( "\"z+=+%283+%2B-+sqrt%28+%28-3%29%5E2-4%281%29%28-4%29+%29%29%2F%282%281%29%29\" Negate \"-3\" to get \"3\". \r
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\n" ); document.write( "\n" ); document.write( "\"z+=+%283+%2B-+sqrt%28+9-4%281%29%28-4%29+%29%29%2F%282%281%29%29\" Square \"-3\" to get \"9\". \r
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\n" ); document.write( "\n" ); document.write( "\"z+=+%283+%2B-+sqrt%28+9--16+%29%29%2F%282%281%29%29\" Multiply \"4%281%29%28-4%29\" to get \"-16\"\r
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\n" ); document.write( "\n" ); document.write( "\"z+=+%283+%2B-+sqrt%28+9%2B16+%29%29%2F%282%281%29%29\" Rewrite \"sqrt%289--16%29\" as \"sqrt%289%2B16%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"z+=+%283+%2B-+sqrt%28+25+%29%29%2F%282%281%29%29\" Add \"9\" to \"16\" to get \"25\"\r
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\n" ); document.write( "\n" ); document.write( "\"z+=+%283+%2B-+sqrt%28+25+%29%29%2F%282%29\" Multiply \"2\" and \"1\" to get \"2\". \r
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\n" ); document.write( "\n" ); document.write( "\"z+=+%283+%2B-+5%29%2F%282%29\" Take the square root of \"25\" to get \"5\". \r
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\n" ); document.write( "\n" ); document.write( "\"z+=+%283+%2B+5%29%2F%282%29\" or \"z+=+%283+-+5%29%2F%282%29\" Break up the expression. \r
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\n" ); document.write( "\n" ); document.write( "\"z+=+%288%29%2F%282%29\" or \"z+=++%28-2%29%2F%282%29\" Combine like terms. \r
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\n" ); document.write( "\n" ); document.write( "\"z+=+4\" or \"z+=+-1\" Simplify.\r
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\n" ); document.write( "\n" ); document.write( "\"z+=+4\" Start with the first solution\r
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\n" ); document.write( "\n" ); document.write( "\"x%5E%28-2%29+=+4\" Plug in \"z=x%5E%28-2%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"1%2Fx%5E2+=+4\" Rewrite the left side with a positive exponent.\r
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\n" ); document.write( "\n" ); document.write( "\"1=4x%5E2\" Multiply both sides by \"x%5E2\".\r
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\n" ); document.write( "\n" ); document.write( "\"x%5E2=1%2F4\" Divide both sides by 4 and rearrange the equation\r
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\n" ); document.write( "\n" ); document.write( "\"x=sqrt%281%2F4%29\" or \"x=-sqrt%281%2F4%29\" Take the square root of both sides (don't forget the plus/minus)\r
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\n" ); document.write( "\n" ); document.write( "\"x=1%2F2\" or \"x=-1%2F2\" Take the square root of \"1%2F4\" to get \"1%2F2\"\r
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\n" ); document.write( "\n" ); document.write( "So the first two solutions are \"x=1%2F2\" or \"x=-1%2F2\"\r
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\n" ); document.write( "\n" ); document.write( "\"z+=+-1\" Start with the second solution\r
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\n" ); document.write( "\n" ); document.write( "\"x%5E%28-2%29+=+-1\" Plug in \"z=x%5E%28-2%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"1%2Fx%5E2+=+-1\" Rewrite the left side with a positive exponent.\r
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\n" ); document.write( "\n" ); document.write( "\"1=-x%5E2\" Multiply both sides by \"x%5E2\"\r
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\n" ); document.write( "\n" ); document.write( "\"x%5E2=-1\" Divide both sides by -1 and rearrange the equation.\r
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\n" ); document.write( "\n" ); document.write( "\"x=sqrt%28-1%29\" or \"x=-sqrt%28-1%29\" Take the square root of both sides (don't forget the plus/minus)\r
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\n" ); document.write( "\n" ); document.write( "\"x=i\" or \"x=-i\" Simplify (note: \"i=sqrt%28-1%29\"\r
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\n" ); document.write( "\n" ); document.write( "So the next two solutions are \"x=i\" or \"x=-i\"\r
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\n" ); document.write( "\n" ); document.write( "Answer:\r
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\n" ); document.write( "\n" ); document.write( "So the solutions are \"x=1%2F2\", \"x=-1%2F2\", \"x=i\" or \"x=-i\"
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