document.write( "Question 1136757: Solve the equation x^4-13x^2+30?
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Algebra.Com's Answer #754575 by ikleyn(52814) $\"\"$ $\"About$

You can put this solution on YOUR website!
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\n" ); document.write( "\n" ); document.write( "            First, it is not an equation, since it has no right side and the equality sign.\r
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\n" ); document.write( "\n" ); document.write( "            So, we can talk about a polynomial, but not about equation.\r
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\n" ); document.write( "\n" ); document.write( "            And the question, if to formulate it correctly, should be THIS :\r
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document.write( "                Find the roots of this polynomial.\r\n" );
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\n" ); document.write( "\n" ); document.write( " Second, the solution and the answer by @Boreal both are incorrect, since his factoring is incorrect.\r
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\n" ); document.write( "\n" ); document.write( " Below find the correct solution.\r
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document.write( "Introduce new variable  u = x^2.\r\n" );
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document.write( "Then your polynomial takes the form\r\n" );
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document.write( "    u^2 - 13u + 30\r\n" );
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document.write( "It can be factored in this way\r\n" );
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document.write( "    u^2 - 13u + 30 = (u-3)*(u-10) \r\n" );
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document.write( "so, it has the roots  u = 3  and  u = 10, both positive.\r\n" );
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document.write( "It means, that the original polynomial has 4 (four) real roots  , ,    and  .    ANSWER\r\n" );
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\n" ); document.write( "\n" ); document.write( "Solved.\r
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