document.write( "Question 985473: Let P(x)=x^3-2x^2-13x-10
\n" ); document.write( "a.determine whether x-5 is a factor if P(x).
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\n" ); document.write( "c.find a complete factorization of P(x).
\n" ); document.write( "d. Solve the equation P(x)=0.
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Algebra.Com's Answer #606343 by ikleyn(52790)\"\" \"About 
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\n" ); document.write( "\n" ); document.write( "a.  To determine whether  x-5  is a factor of  P(x),  calculate  P(5),  i.e.  simply substitute the value of  5  into the polynomial.  You will get \r
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\n" ); document.write( "\n" ); document.write( "P(5) = \"5%5E3+-+2%2A5%5E2+-+13%2A5+-+10\" = 125 - 50 - 65 - 10 = 0.\r
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\n" ); document.write( "\n" ); document.write( "According wi the  Remainder Theorem  (see,  for example,  the lesson  Divisibility of polynomial f(x) by binomial x-a  in this site),  the binom  x-5  is a factor of the polynomial  P(x).\r
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\n" ); document.write( "\n" ); document.write( "b.  Make the long division of the polynomial  P(x) = \"x%5E3-2x%5E2-13x-10\"  by  \"%28x-5%29\".  You will get \r
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\n" ); document.write( "\n" ); document.write( "\"x%5E3-2x%5E2-13x-10\" = \"%28x-5%29\".\"%28x%5E2+%2B+3x+%2B+2%29\". \r
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\n" ); document.write( "\n" ); document.write( "So,  the polynomial  \"%28x%5E2+%2B+3x+%2B+2%29\"  is another factor of the polynomial  P(x). \r
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\n" ); document.write( "\n" ); document.write( "c.  The quadratic polynomial  \"x%5E2+%2B+3x+%2B+2\"  has the roots  \"x%5B1%5D\" = -1  and  \"x%5B2%5D\" = -2  (use the quadratic formula  Introduction into Quadratic Equations  or the Vieta's theorem  Solving quadratic equations without quadratic formula,  lessons in this site)\r
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\n" ); document.write( "\n" ); document.write( "It implies that  \"x%5E2+%2B+3x+%2B+2\" = \"%28x%2B1%29\".\"%28x%2B2%29\". \r
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\n" ); document.write( "\n" ); document.write( "Therefore, \r
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\n" ); document.write( "\n" ); document.write( "P(x) = \"%28x-5%29\".\"%28x%2B1%29\".\"%28x%2B2%29\" \r
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\n" ); document.write( "\n" ); document.write( "is the complete factorization of the polynomial  P(x) = \"x%5E3-2x%5E2-13x-10\".\r
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\n" ); document.write( "\n" ); document.write( "d.  Since P(x) = \"x%5E3-2x%5E2-13x-10\" = \"%28x-5%29\".\"%28x%2B1%29\".\"%28x%2B2%29\",  the roots of the polynomial \"x%5E3-2x%5E2-13x-10\" are 5, -1 and -2. \r
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\n" ); document.write( "\n" ); document.write( "The solution is completed.\r
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