document.write( "Question 927008: Let P(x) = kx^3 + 2k^2x^2 + k^3. Find the sum of all real numbers k for which x-2 is a factor of P(x).\r
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document.write( "Please help! \n" );
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Algebra.Com's Answer #562630 by jim_thompson5910(35256) ![]() You can put this solution on YOUR website! Using the remainder theorem, if x-k is a factor of P(x), then P(k) = 0.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "So that means if x-2 is a factor of P(x), then P(2) = 0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Plug x = 2 into P(x) and set it equal to 0\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "P(x) = kx^3 + 2k^2x^2 + k^3\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "P(x) = k(2)^3 + 2k^2(2)^2 + k^3\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "P(x) = 8k+8k^2+k^3\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "0 = 8k+8k^2+k^3\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "8k+8k^2+k^3 = 0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "k^3+8k^2+8k = 0\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Now we solve for k\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "k^3+8k^2+8k = 0\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "k*(k^2+8k+8) = 0\r \n" ); document.write( " \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "I'll let you finish up. One of those factors will give you complex (nonreal) solutions. \n" ); document.write( "------------------------------------------------------------------------------------------------------------------------\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "If you need more one-on-one help, email me at jim_thompson5910@hotmail.com. You can ask me a few more questions for free, but afterwards, I would charge you ($2 a problem to have steps shown or $1 a problem for answer only).\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Alternatively, please consider visiting my website: http://www.freewebs.com/jimthompson5910/home.html and making a donation. Any amount is greatly appreciated as it helps me a lot. This donation is to support free tutoring. Thank you.\r \n" ); document.write( " \n" ); document.write( "\n" ); document.write( "Jim\r \n" ); document.write( "\n" ); document.write( "------------------------------------------------------------------------------------------------------------------------ \n" ); document.write( " |