document.write( "Question 144078: Hi, I'm Michele and I could really use someones help on my problem. I will be greatful and very thankful for who ever will help me. Thank You for your help.\r
\n" ); document.write( "\n" ); document.write( "1.Find k if the following system of equations has a unique solution
\n" ); document.write( "2x + (k - 1)y = 6
\n" ); document.write( "3x + (2k + 1)y = 9\r
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\n" ); document.write( "\n" ); document.write( "2.Find k if the following system of equations has infinite solutions
\n" ); document.write( "kx + 3y = k - 3
\n" ); document.write( "12x + ky = k\r
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\n" ); document.write( "\n" ); document.write( "3.Find k if the following system of equations has no solution
\n" ); document.write( "3x + 2y = 6
\n" ); document.write( "kx + (k - 1)y = 9\r
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Algebra.Com's Answer #104911 by stanbon(75887)\"\" \"About 
You can put this solution on YOUR website!
1.Find k if the following system of equations has a unique solution
\n" ); document.write( "2x + (k - 1)y = 6
\n" ); document.write( "3x + (2k + 1)y = 9
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\n" ); document.write( "Multiply thru 1st by 3 ; Multiply thru 2nd by 2 to get:
\n" ); document.write( "6x + (3k-3)y = 18
\n" ); document.write( "6x + (4k+2)y = 18
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\n" ); document.write( "Subtract 1st from 2nd to get:
\n" ); document.write( "[4k+2-(3k-3)]y = 0
\n" ); document.write( "[k+5] y = 0
\n" ); document.write( "Comment: y is a variable so may not always be zero
\n" ); document.write( "k+5 = 0 when k=-5
\n" ); document.write( "As long as k is not -5, y will be zero and x will be 3
\n" ); document.write( "So the system will have a unique solution as long as k is not equal to -5.
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\n" ); document.write( "\n" ); document.write( "2.Find k if the following system of equations has infinite solutions
\n" ); document.write( "kx + 3y = k - 3
\n" ); document.write( "12x + ky = k
\n" ); document.write( "-------
\n" ); document.write( "The system has infinite solutions if the slopes and the intercepts are the same
\n" ); document.write( "Put them in slope-intercept form:
\n" ); document.write( "y = (-k/3)x + (k-3)/3
\n" ); document.write( "y = (-12/k)x + 1
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\n" ); document.write( "Equating slopes: -k/3 = -12/k ; k = 6
\n" ); document.write( "Equating intercepts: (k-3)/3 = 1 ; k = 6
\n" ); document.write( "Conclusion: infinitely many solutions if k = 6
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\n" ); document.write( "\n" ); document.write( "Find k if the following system of equations has no solution
\n" ); document.write( "3x + 2y = 6
\n" ); document.write( "kx + (k - 1)y = 9
\n" ); document.write( "--------
\n" ); document.write( "No solutions if slopes are the same and intercepts are not.
\n" ); document.write( "y = (-3/2)x + 3
\n" ); document.write( "y = (-k/(k-1)x + 9/(k-1)
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\n" ); document.write( "Equating slopes: -3/2 = -k/(k-1) ; -2k = -3k+3 ; k = 3
\n" ); document.write( "Equatiing intercepts: 3 = 9/(k-1) ; k-1 = 3 ; k = 4
\n" ); document.write( "-------------
\n" ); document.write( "Conclusion: No solutions if k = 3
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\n" ); document.write( "Cheers,
\n" ); document.write( "Stan H.
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