document.write( "Question 913163: Solve: 16^(x) + 4^(x+1) - 3 = 0 \r
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Algebra.Com's Answer #554330 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
\"16%5E%28x%29+%2B+4%5E%28x%2B1%29+-+3+=+0\"\r
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\n" ); document.write( "\n" ); document.write( "\"%284%5E2%29%5Ex+%2B+4%5E%28x%2B1%29+-+3+=+0\"\r
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\n" ); document.write( "\n" ); document.write( "\"4%5E%282x%29+%2B+4%5E%28x%2B1%29+-+3+=+0\"\r
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\n" ); document.write( "\n" ); document.write( "\"%284%5Ex%29%5E2+%2B+4%5E%28x%2B1%29+-+3+=+0\"\r
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\n" ); document.write( "\n" ); document.write( "\"%284%5Ex%29%5E2+%2B+%284%5Ex%29%2A%284%5E%281%29%29+-+3+=+0\"\r
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\n" ); document.write( "\n" ); document.write( "\"%284%5Ex%29%5E2+%2B+%284%5Ex%29%2A%284%29+-+3+=+0\"\r
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\n" ); document.write( "\n" ); document.write( "\"%284%5Ex%29%5E2+%2B+4%284%5Ex%29+-+3+=+0\"\r
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\n" ); document.write( "\n" ); document.write( "\"z%5E2+%2B4z+-+3+=+0\" Let \"z+=+4%5Ex\"\r
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\n" ); document.write( "\n" ); document.write( "Use the quadratic formula to get \"z+=+-2%2Bsqrt%287%29\" or \"z+=+-2-sqrt%287%29\"\r
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\n" ); document.write( "\n" ); document.write( "The steps for the quadratic formula are lengthy and I feel they would clutter up this solution page. Let me know if you need to see the steps to getting those solutions for z.\r
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\n" ); document.write( "\n" ); document.write( "The solutions in terms of z are \"z+=+-2%2Bsqrt%287%29\" or \"z+=+-2-sqrt%287%29\"\r
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\n" ); document.write( "\n" ); document.write( "We ultimately want solutions in terms of x.\r
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\n" ); document.write( "\n" ); document.write( "Plug in the first solution for z to get the first solution for x.\r
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\n" ); document.write( "\n" ); document.write( "\"z+=+4%5Ex\"\r
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\n" ); document.write( "\n" ); document.write( "\"-2%2Bsqrt%287%29+=+4%5Ex\"\r
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\n" ); document.write( "\n" ); document.write( "\"4%5Ex+=+-2%2Bsqrt%287%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+log%284%2C%28-2%2Bsqrt%287%29%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "So the first solution is \"x+=+log%284%2C%28-2%2Bsqrt%287%29%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "Using a calculator, we get log(-2+sqrt(7))/log(4) = -0.3154747\r
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\n" ); document.write( "\n" ); document.write( "Plug in the second solution for z to get the second solution for x.\r
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\n" ); document.write( "\n" ); document.write( "\"z+=+4%5Ex\"\r
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\n" ); document.write( "\n" ); document.write( "\"-2-sqrt%287%29+=+4%5Ex\"\r
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\n" ); document.write( "\n" ); document.write( "\"4%5Ex+=+-2-sqrt%287%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"x+=+log%284%2C%28-2-sqrt%287%29%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "So the second solution is \"x+=+log%284%2C%28-2-sqrt%287%29%29%29\"; however, notice how \"-2-sqrt%287%29=-4.64575\" is negative. That means the log of this value is undefined. So log(-2-sqrt(7)) = log(-4.64575) = Undefined\r
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\n" ); document.write( "\n" ); document.write( "Final Answer: \r
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\n" ); document.write( "\n" ); document.write( "The only exact solution is \"x+=+log%284%2C%28-2%2Bsqrt%287%29%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "The only approximate solution is \"x+=+-0.3154747\"\r
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\n" ); document.write( "\n" ); document.write( "Let me know if you need more help or if you need me to explain a step in more detail.
\n" ); document.write( "Feel free to email me at jim_thompson5910@hotmail.com
\n" ); document.write( "or you can visit my website here: http://www.freewebs.com/jimthompson5910/home.html\r
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\n" ); document.write( "\n" ); document.write( "Thanks,\r
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\n" ); document.write( "\n" ); document.write( "Jim \r
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