document.write( "Question 1206674: list ALL roots (rational, irrational, and/or complex) of the given polynomial equation by using the methods discussed in this lesson. SHOW YOUR WORK. \r
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document.write( " x^3 - 5x^2 + 7x - 35 = 0\r
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Algebra.Com's Answer #844234 by math_tutor2020(3817)![]() ![]() ![]() You can put this solution on YOUR website! \n" ); document.write( "Since the leading coefficient is 1, we list the factors of the last term to generate all possible rational roots.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "List of possible rational roots: \n" ); document.write( "1, -1, 5, -5, 7, -7, 35, -35 \n" ); document.write( "List the positive and negative versions of each.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Then plug each of them into the function to see which generates the result of 0. \n" ); document.write( "Let's try x = 1 \n" ); document.write( "f(x) = x^3 - 5x^2 + 7x - 35 \n" ); document.write( "f(1) = (1)^3 - 5(1)^2 + 7(1) - 35 \n" ); document.write( "f(1) = -32 \n" ); document.write( "The nonzero result tells us that x = 1 is not a root. \n" ); document.write( "Every other value but x = 5 will also generate nonzero results. \r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "f(x) = x^3 - 5x^2 + 7x - 35 \n" ); document.write( "f(5) = (5)^3 - 5(5)^2 + 7(5) - 35 \n" ); document.write( "f(5) = 0 \n" ); document.write( "Proving that x = 5 is a root and x-5 is a factor.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Let's apply synthetic division with this root. \n" ); document.write( "
\n" ); document.write( "The last item in the bottom row is 0 which is the remainder. The remainder 0 confirms that x = 5 is indeed a root. \n" ); document.write( "The other items in the bottom row form the quotient.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Quotient = 1x^2 + 0x + 7 = x^2 + 7\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "We determine x^3-5x^2+7x-35 = (x-5)(x^2+7)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Solving x^2+7 = 0 leads to x = i*sqrt(7) and x = -i*sqrt(7) where i = sqrt(-1)\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "The three roots are \n" ); document.write( "x = 5, x = i*sqrt(7) and x = -i*sqrt(7) \n" ); document.write( " \n" ); document.write( " |