document.write( "Question 173400: The equation \"x%5E2-3x-2=0\" has roots \"alpha\" and \"beta\", and the equation \"x%5E2-6x%2Bp=0\" has roots \"k%2Falpha\" and \"k%2Fbeta\". find the value of \"k\" and of \"p\". \n" ); document.write( "
Algebra.Com's Answer #128251 by Edwin McCravy(20054)\"\" \"About 
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The equation \"x%5E2-3x-2=0\" has roots \"alpha\" and \"beta\", and the equation \"x%5E2-6x%2Bp=0\" has roots \"k%2Falpha\" and \"k%2Fbeta\". find the value of \"k\" and of \"p\".
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document.write( "We need to know two things about a quadratic equation of the\r\n" );
document.write( "form \"x%5E2%2Bbx%2Bc=0\"\r\n" );
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document.write( "1.  \"matrix%281%2C2%2Cb%2C%22=%22%29\" the sum of the two roots with the sign changed.\r\n" );
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document.write( "2.  \"matrix%281%2C2%2Cc%2C%22=%22%29\" the product of the two roots.\r\n" );
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document.write( "We use 1 and 2 on the first equation:\r\n" );
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document.write( "Since \"x%5E2-3x-2=0\" has roots \"alpha\" and \"beta\",\r\n" );
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document.write( "Using 1, \"matrix%281%2C3%2C-3%2C%22=%22%2C-%28alpha%2Bbeta%29%29\" \r\n" );
document.write( "multiplying both sides by \"-1\"\r\n" );
document.write( "\"matrix%281%2C3%2C3%2C%22=%22%2Calpha%2Bbeta%29\"\r\n" );
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document.write( "Using 2, \"matrix%281%2C3%2C-2%2C%22=%22%2Calpha%2Abeta%29\" \r\n" );
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document.write( "Now we use 1 and 2 on the second equations:\r\n" );
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document.write( "Since \"x%5E2-6x%2Bp=0\" has roots \"k%2Falpha\" and \"k%2Fbeta\". \r\n" );
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document.write( "Using 1, \"matrix%281%2C3%2C-6%2C%22=%22%2C-%28k%2Falpha%2Bk%2Fbeta%29%29\" \r\n" );
document.write( "multiplying both sides by \"-1\"\r\n" );
document.write( "\"matrix%281%2C3%2C6%2C%22=%22%2Ck%2Falpha%2Bk%2Fbeta%29\"\r\n" );
document.write( "getting the LCD of \"alpha%2Abeta\"\r\n" );
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document.write( "Combine numerators over the LCD:\r\n" );
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document.write( "\"matrix%281%2C3%2C6%2C%22=%22%2C%28k%2Abeta%2Bk%2Aalpha%29%2F%28alpha%2Abeta%29%29\"\r\n" );
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document.write( "Factor out \"k\" on top:\r\n" );
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document.write( "\"matrix%281%2C3%2C6%2C%22=%22%2C%28k%28beta%2Balpha%29%29%2F%28alpha%2Abeta%29%29\"\r\n" );
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document.write( "Now,\r\n" );
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document.write( "since we have above that \"matrix%281%2C3%2C3%2C%22=%22%2Calpha%2Bbeta%29\",\r\n" );
document.write( "and since \"%28beta%2Balpha%29=alpha%2Bbeta\", we can replace\r\n" );
document.write( "\"beta%2Balpha\" by \"3\",\r\n" );
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document.write( "and\r\n" );
document.write( "since we have above that \"matrix%281%2C3%2C-2%2C%22=%22%2Calpha%2Abeta%29\",\r\n" );
document.write( "we can replace \"alpha%2Abeta\" by -2,\r\n" );
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document.write( "\"matrix%281%2C3%2C6%2C%22=%22%2C%28k%28beta%2Balpha%29%29%2F%28alpha%2Abeta%29%29\"\r\n" );
document.write( "\"matrix%281%2C3%2C6%2C%22=%22%2C%28k%283%29%29%2F%28-2%29%29\"\r\n" );
document.write( "\"matrix%281%2C3%2C6%2C%22=%22%2C-3k%2F2%29\"\r\n" );
document.write( "Multiply both sides by \"2\"\r\n" );
document.write( "\"matrix%281%2C3%2C12%2C%22=%22%2C-3k%29\"\r\n" );
document.write( "Divide both sides by \"-3\"\r\n" );
document.write( "\"matrix%281%2C3%2C-4%2C%22=%22%2Ck%29\"\r\n" );
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document.write( "So the value of \"k\" is \"-4\"\r\n" );
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document.write( "Using 2 on the second equation, \r\n" );
document.write( "\"matrix%281%2C3%2Cp%2C%22=%22%2C%28k%2Falpha%29%28k%2Fbeta%29%29%29\" \r\n" );
document.write( "But since \"k=-4\",\r\n" );
document.write( "\"matrix%281%2C3%2Cp%2C%22=%22%2C%28%28-4%29%2Falpha%29%28%28-4%29%2Fbeta%29%29%29\"\r\n" );
document.write( "\"matrix%281%2C3%2Cp%2C%22=%22%2C16%2F%28alpha%2Abeta%29%29\"\r\n" );
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document.write( "Now since from above, we have \"matrix%281%2C3%2C-2%2C%22=%22%2Calpha%2Abeta%29\",\r\n" );
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document.write( "\"matrix%281%2C3%2Cp%2C%22=%22%2C16%2F%28alpha%2Abeta%29%29\" becomes\r\n" );
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document.write( "\"matrix%281%2C3%2Cp%2C%22=%22%2C16%2F%28-2%29%29\"\r\n" );
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document.write( "\"matrix%281%2C3%2Cp%2C%22=%22%2C-8%29\"\r\n" );
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document.write( "So the value of \"p\" is \"-8\"\r\n" );
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document.write( "Edwin
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