document.write( "Question 986181: Three roots of a fourth-degree polynomial equation with rational coefficients are 5+√3, –17, and 2-√4. Which number also is a root of the equation?
\n" ); document.write( "A. 17
\n" ); document.write( "B. 2+√4
\n" ); document.write( "C. 4-√2
\n" ); document.write( "D. 5-√3
\n" ); document.write( "How does this make sense? I thought that if you switched the addition/subtraction symbol, then you will have the other root. So shouldn't A, B, and D all be correct?
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Algebra.Com's Answer #606984 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
Since \"sqrt%284%29=2\", we know that \"2-sqrt%284%29=2-2+=+0\". They made this root a bit more complicated than it had to be to confuse you. The three roots, as simple as they can get, are given as \"5%2Bsqrt%283%29\", \"-17\", and \"0\"\r
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\n" ); document.write( "\n" ); document.write( "Rule: if you have a polynomial with rational coefficients, and you have a root \"a%2Bb%2Asqrt%28c%29\", then \"a-b%2Asqrt%28c%29\" must also be a root as well.\r
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\n" ); document.write( "\n" ); document.write( "So if \"5%2Bsqrt%283%29\" is a root, then \"5-sqrt%283%29\" must also be a root (note: a = 5, b = 1, c = 3 in this case)\r
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\n" ); document.write( "\n" ); document.write( "Final Answer: Choice D) \"5-sqrt%283%29\"
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