document.write( "Question 92096: Use Descartes' Rule of Signs to determine the possible number of positive and negative zeros for the function P(x) = -3x^5 -7x^3 -4x - 5. \n" ); document.write( "
Algebra.Com's Answer #66953 by jim_thompson5910(35256)\"\" \"About 
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\n" ); document.write( "First lets find the number of possible positive real zeros:\r
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\n" ); document.write( "\n" ); document.write( "For \"-3x%5E5-7x%5E3-4x-5\", simply count the sign changes\r
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\n" ); document.write( "\n" ); document.write( "By looking at \"-3x%5E5-7x%5E3-4x-5\" we can see that there are no sign changes (all the terms are negative).\r
\n" ); document.write( "\n" ); document.write( "So there are no positive zeros\r
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\n" ); document.write( "\n" ); document.write( "Now lets find the number of possible negative real zeros\r
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\n" ); document.write( "\n" ); document.write( "---------------\r
\n" ); document.write( "\n" ); document.write( "First we need to find \"f%28-x%29\":\r
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\n" ); document.write( "\n" ); document.write( "\"f%28-x%29=-3%28-x%29%5E5-7%28-x%29%5E3-4%28-x%29-5\" Plug in -x (just replace every x with -x)\r
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\n" ); document.write( "\n" ); document.write( "\"f%28-x%29=3x%5E5%2B7x%5E3%2B4x-5\" Simplify (note: if the exponent of the given term is odd, simply negate the sign of the term)\r
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\n" ); document.write( "\n" ); document.write( "So \"f%28-x%29=3x%5E5%2B7x%5E3%2B4x-5\"\r
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\n" ); document.write( "\n" ); document.write( "Now lets count the sign changes for \"3x%5E5%2B7x%5E3%2B4x-5\":\r
\n" ); document.write( "\n" ); document.write( "Here is the list of sign changes:\r
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  1. \"4x\" to \"-5\" (positive to negative)
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\n" ); document.write( "\n" ); document.write( "So for \"3x%5E5%2B7x%5E3%2B4x-5\" there are a maximum of 1 negative zero\r
\n" ); document.write( "\n" ); document.write( "So there is exactly one negative zero\r
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\n" ); document.write( "\n" ); document.write( "Summary:\r
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\n" ); document.write( "\n" ); document.write( "So there are 0 positive zeros and 1 negative zero
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