document.write( "Question 1209218: Let a and b be the solutions to 5x^2 - 11x + 4 = -x^2 + 5x - 3. Find
\n" ); document.write( "a^2/b + b^2/a
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Algebra.Com's Answer #847856 by math_tutor2020(3817)\"\" \"About 
You can put this solution on YOUR website!

\n" ); document.write( "Answer: 520/63\r
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\n" ); document.write( "\n" ); document.write( "Explanation\r
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\n" ); document.write( "\n" ); document.write( "5x^2 - 11x + 4 = -x^2 + 5x - 3
\n" ); document.write( "rearranges to
\n" ); document.write( "6x^2 - 16x + 7 = 0
\n" ); document.write( "after getting everything to one side.\r
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\n" ); document.write( "\n" ); document.write( "Then divide each term by the leading coefficient to arrive at
\n" ); document.write( "x^2 - (8/3)x + 7/6 = 0
\n" ); document.write( "This is so we have a leading coefficient of 1.\r
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\n" ); document.write( "\n" ); document.write( "Due to Vieta's Theorems (specifically the quadratic versions), we know these two facts:
  • The roots add to the negative of the x coefficient.
  • The roots multiply to the constant term.
These rules apply only when the leading coefficient is 1.\r
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\n" ); document.write( "\n" ); document.write( "Based on those two rules we can say
\n" ); document.write( "a+b = 8/3
\n" ); document.write( "a*b = 7/6
\n" ); document.write( "Let's call these equations (1) and (2)\r
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\n" ); document.write( "\n" ); document.write( "Another useful equation we'll need is
\n" ); document.write( "a^2+b^2 = (a+b)^2 - 2ab
\n" ); document.write( "which is derived from
\n" ); document.write( "(a+b)^2 = a^2+2ab+b^2\r
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\n" ); document.write( "\n" ); document.write( "Let's label the equation a^2+b^2 = (a+b)^2 - 2ab as equation (3).\r
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\n" ); document.write( "\n" ); document.write( "\"%28a%5E2%29%2Fb+%2B+%28b%5E2%29%2Fa\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "= \"%28a%5E3%29%2F%28ab%29+%2B+%28b%5E3%29%2F%28ab%29\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "= \"%28a%5E3%2Bb%5E3%29%2F%28ab%29\"\r
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\n" ); document.write( "\n" ); document.write( "= \"%28%28a%2Bb%29%28a%5E2-ab%2Bb%5E2%29%29%2F%28ab%29\" Apply the sum of cubes factoring rule\r
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\n" ); document.write( "\n" ); document.write( "= \"%28%28a%2Bb%29%28a%5E2%2Bb%5E2-ab%29%29%2F%28ab%29\" \r
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\n" ); document.write( "\n" ); document.write( "= \"%28%28a%2Bb%29%28%28a%2Bb%29%5E2-2ab-ab%29%29%2F%28ab%29\" Use equation (3)\r
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\n" ); document.write( "\n" ); document.write( "= \"%28%28a%2Bb%29%28%28a%2Bb%29%5E2-3ab%29%29%2F%28ab%29\" \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "= \"%28%288%2F3%29%28%288%2F3%29%5E2-3%287%2F6%29%29%29%2F%287%2F6%29\" Use equations (1) and (2). \r
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\n" ); document.write( "\n" ); document.write( "= \"%288%2F3%29%2864%2F9-7%2F2%29%2A%286%2F7%29\" \r
\n" ); document.write( "\n" ); document.write( "
\n" ); document.write( "= \"%288%2F3%29%28128%2F18+-+63%2F18%29%2A%286%2F7%29\"\r
\n" ); document.write( "\n" ); document.write( "
\n" ); document.write( "= \"%288%2F3%29%2865%2F18%29%2A%286%2F7%29\" \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "= \"%288%2A65%2A6%29%2F%283%2A18%2A7%29\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "= \"3120%2F378\"\r
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\n" ); document.write( "\n" ); document.write( "= \"%286%2A520%29%2F%286%2A63%29\"\r
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\n" ); document.write( "\n" ); document.write( "= \"520%2F63\"\r
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\n" ); document.write( "\n" ); document.write( "Therefore we determine that \"%28a%5E2%29%2Fb+%2B+%28b%5E2%29%2Fa+=+520%2F63\" where a,b are the roots of 5x^2 - 11x + 4 = -x^2 + 5x - 3\r
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\n" ); document.write( "\n" ); document.write( "I used GeoGebra to verify the solution is correct.\r
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\n" ); document.write( "\n" ); document.write( "520/63 = 8.253968 approximately\r
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\n" ); document.write( "\n" ); document.write( "More practice is found here
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