document.write( "Question 686945: Find all integers k such that the trinomial is a perfect square trinomial \r
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Algebra.Com's Answer #424982 by Edwin McCravy(20055)\"\" \"About 
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document.write( "The other tutors did not mention that there are two answers.\r\n" );
document.write( "The problem did not state that k must be a POSITIVE integer.  It\r\n" );
document.write( "just stated that k must be an integer, and an integer can be\r\n" );
document.write( "POSITIVE or NEGATIVE.  So we must give both answers.\r\n" );
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document.write( "If 64x² + kxy + y²\r\n" );
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document.write( "is a perfect square it will have to factor as\r\n" );
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document.write( "either  (8x + y)² or as (8x - y)²\r\n" );
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document.write( "If it factors as (8x + y)², then that is the same as\r\n" );
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document.write( "(8x + y)(8x + y) = 64x² + 16xy + y².  In that case the\r\n" );
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document.write( "middle term +kxy would equal to +16xy and so k would be 16.\r\n" );
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document.write( "If it factors as (8x - y)², then that is the same as\r\n" );
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document.write( "(8x - y)(8x - y) = 64x² - 16xy + y².  In that case the\r\n" );
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document.write( "middle term +kxy would equal to -16xy and so k would be -16.\r\n" );
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document.write( "Answer: Two possibilities: k = 16, k = -16\r\n" );
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document.write( "Edwin
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