document.write( "Question 206101: I really need some help for this problems because I have been confuse of this problems since the start and now the Examination is coming near and this is going to be added, I really will appreciate some help in this questions:\r
\n" ); document.write( "\n" ); document.write( "---find the value of k so that the equation \"+3x%5E2-7x%2Bk=0+\" will have equal roots.\r
\n" ); document.write( "\n" ); document.write( "---find the value of k so that the equation \"+3x%5E2-%285%2Bk%29x-17=0+\" will have one roots numerically equal but opposite in sign\r
\n" ); document.write( "\n" ); document.write( "--what should be the range of the value of k so that the equation \"+2x%5E2%2B3kx-9=0+\" will have real and unequal roots.\r
\n" ); document.write( "\n" ); document.write( "---what should be the value of k so that the equation \"+x%5E2%2B%28k-2%29x%2B4=0+\"
\n" ); document.write( "will have equal roots?
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Algebra.Com's Answer #155680 by Edwin McCravy(20055)\"\" \"About 
You can put this solution on YOUR website!
I really need some help for this problems because I have been confuse of this problems since the start and now the Examination is coming near and this is going to be added, I really will appreciate some help in this questions:\r
\n" ); document.write( "\n" ); document.write( "---find the value of k so that the equation \"+3x%5E2-7x%2Bk=0+\" will have equal roots.
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document.write( "Find the discriminant \"b%5E2-4ac=%28-7%29%5E2-4%283%29%28k%29=49-12k\"\r\n" );
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document.write( "To have equal roots the discriminant must equal 0, so\r\n" );
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document.write( "\"49-12k=0\"\r\n" );
document.write( "\"-12k=-49\"\r\n" );
document.write( "\"k=%28-49%29%2F%28-12%29\"\r\n" );
document.write( "\"k=49%2F12\"\r\n" );
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document.write( "To check, we substitute \"49%2F12\" for \"k\" in\r\n" );
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document.write( "\"+3x%5E2-7x%2Bk=0+\"\r\n" );
document.write( "\"+3x%5E2-7x%2B49%2F12=0+\"\r\n" );
document.write( "Multiply through by 12 to clear of fractions:\r\n" );
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document.write( "\"12%2A3x%5E2-12%2A7x%2B12%2A%2849%2F12%29=12%2A0\"\r\n" );
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document.write( "\"36x%5E2-84x%2B49=0\"\r\n" );
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document.write( "\"%286x-7%29%286x-7%29=0\"\r\n" );
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document.write( "\"6x-7=0\"; \"6x-7=0\"\r\n" );
document.write( "\"6x=7\"  ; \"6x=7\"\r\n" );
document.write( "\"x=7%2F6\" ; \"x=7%2F6\"\r\n" );
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document.write( "So the roots are equal. \r\n" );
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\n" ); document.write( "---find the value of k so that the equation \"+3x%5E2-%285%2Bk%29x-17=0+\" will have one roots numerically equal but opposite in sign
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\r\n" );
document.write( "Then it will have to be true that we also get zero when we \r\n" );
document.write( "substitute \"-x\" for \"x\":\r\n" );
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document.write( "\"+3%28-x%29%5E2-%285%2Bk%29%28-x%29-17=0+\"\r\n" );
document.write( "\"3x%5E2%2B%285%2Bk%29x-17=0\"\r\n" );
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document.write( "And since we started with \"+3x%5E2-%285%2Bk%29x-17=0+\"\r\n" );
document.write( "We can set the left sides equal:\r\n" );
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document.write( "\"3x%5E2%2B%285%2Bk%29x-17=+3x%5E2-%285%2Bk%29x-17=0+\"\r\n" );
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document.write( "\"3x%5E2%2B5x%2Bkx-17=+3x%5E2-5x-kx-17=0+\"\r\n" );
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document.write( "\"10x%2B2kx=0+\"\r\n" );
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document.write( "Divide thru by 2\r\n" );
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document.write( "\"5x%2Bkx=0\"\r\n" );
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document.write( "Factor out x\r\n" );
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document.write( "\"x%285%2Bk%29=0\"\r\n" );
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document.write( "\"x=0\"; \"5%2Bk=0\" \r\n" );
document.write( "           \"k=-5\"\r\n" );
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document.write( "So the value of k that will cause the\r\n" );
document.write( "roots to be numerically equal but opposite\r\n" );
document.write( "in sign.\r\n" );
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document.write( "Check by substituting -5 for k and solve:\r\n" );
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document.write( "\"+3x%5E2-%285%2Bk%29x-17=0+\"\r\n" );
document.write( "\"+3x%5E2-%285%2B%28-5%29%29x-17=0+\"\r\n" );
document.write( "\"+3x%5E2-17=0+\"\r\n" );
document.write( "\"3x%5E2=17\"\r\n" );
document.write( "\"x%5E2=17%2F3\"\r\n" );
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document.write( "\"sqrt%2851%29%2F3\" and \"-sqrt%2851%29%2F3\" are numerically \r\n" );
document.write( "equal but opposite in sign.\r\n" );
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document.write( "

\n" ); document.write( "--what should be the range of the value of k so that the equation
\n" ); document.write( "\"+2x%5E2%2B3kx-9=0+\" will have real and unequal roots.
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\r\n" );
document.write( "That is when the discriminant is positive\r\n" );
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document.write( "Find the discriminant \"b%5E2-4ac=%283k%29%5E2-4%282%29%28-9%29=9k%5E2%2B72\"\r\n" );
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document.write( "\"Positive\" means the same as \"greater than 0\"\r\n" );
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document.write( "So we set \"9k%5E2%2B72%3E0\"\r\n" );
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document.write( "Divide through by 9\r\n" );
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document.write( "\"k%5E2%2B8%3E0\"\r\n" );
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document.write( "Since \"k%5E2\" is never negative the left side will always\r\n" );
document.write( "positive no matter what value of k we use, so all values of \r\n" );
document.write( "k will yield real and unequal roots.\r\n" );
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document.write( "So \"-infinity%3Ck%3Cinfinity\"\r\n" );
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document.write( "

\n" ); document.write( "---what should be the value of k so that the equation \"+x%5E2%2B%28k-2%29x%2B4=0+\"
\n" ); document.write( "will have equal roots?
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\r\n" );
document.write( "Find the discriminant \"b%5E2-4ac=%28k-2%29%5E2-4%281%29%284%29=4%28k-2%29%5E2-16\"\r\n" );
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document.write( "To have equal roots the discriminant must equal 0, so\r\n" );
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document.write( "\"4%28k-2%29%5E2-16=0\"\r\n" );
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document.write( "Divide thru by 4\r\n" );
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document.write( "\"%28k-2%29%5E2-4=0\"\r\n" );
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document.write( "\"%28k-2%29%5E2=4\"\r\n" );
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document.write( "\"k-2=%22%22%2B-sqrt%284%29\"\r\n" );
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document.write( "\"k-2=%22%22%2B-2\"\r\n" );
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document.write( "\"k=2%2B-2\"\r\n" );
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document.write( "Using the \"%22%2B%22\", \"k=2%2B2=4\"\r\n" );
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document.write( "Using the \"%22-%22\", \"k=2-2=0\"\r\n" );
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document.write( "Edwin
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