document.write( "Question 94554: Matrices-and-determiminant/94544 (2007-08-26 21:09:08): I promise this is the last time I will beg for your help PLEASE HELP =I will pay you thru pay pal if I can get this answered in the next 1/2 hr. I am willing to pay PLEASE I AM DESPERate
\n" ); document.write( "Solve the system of equations by the Gaussian elimination method:
\n" ); document.write( "1. Solve the system of equations by the Gaussian elimination method:
\n" ); document.write( "2x+y-3z=1
\n" ); document.write( "3x-y+4z=6
\n" ); document.write( "x+2y-z=9
\n" ); document.write( "2. Solve the system of equations by the Gaussian elimination method:
\n" ); document.write( "x-y+z=17
\n" ); document.write( "x+y-z=-11
\n" ); document.write( "x-y-z=9
\n" ); document.write( "Again thank you in advance for your help.
\n" ); document.write( "0 solutions
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Algebra.Com's Answer #68895 by chitra(359)\"\" \"About 
You can put this solution on YOUR website!
Alright here goes the solution for your question on solving equations by the method of gaussian elimination\r
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\n" ); document.write( "\n" ); document.write( "2x + y - 3z = 1\r
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\n" ); document.write( "\n" ); document.write( "3x - y + 4z = 6\r
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\n" ); document.write( "\n" ); document.write( "x + 2y - z = 9 \r
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\n" ); document.write( "\n" ); document.write( "The given system can be written in the augmented form as: \r
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\n" ); document.write( "\n" ); document.write( "[2 1 -3 : 1]
\n" ); document.write( "[3 -1 4 : 6]
\n" ); document.write( "[1 2 -1 : 9]\r
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\n" ); document.write( "\n" ); document.write( "The operations performed are: \r
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\n" ); document.write( "\n" ); document.write( "We shall first interchange the first row with the third row. \r
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\n" ); document.write( "\n" ); document.write( "[1 2 -1 : 9]
\n" ); document.write( "[3 -1 4 : 6]
\n" ); document.write( "[2 1 -3 : 1]\r
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\n" ); document.write( "\n" ); document.write( "Next: R2 - 3R1 and R3 - 2R1 are the operations which follow\r
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\n" ); document.write( "\n" ); document.write( "[1 2 -1 : 9]
\n" ); document.write( "[0 -7 7 : -21]
\n" ); document.write( "[0 -3 -1 : -17] \r
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\n" ); document.write( "\n" ); document.write( "R3 - R2 is the next opeartion.\r
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\n" ); document.write( "\n" ); document.write( "[1 2 -1 : 9]
\n" ); document.write( "[0 -7 7 : -21]
\n" ); document.write( "[0 4 -8 : 4] \r
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\n" ); document.write( "\n" ); document.write( "Lets divide R2/7 and R3/4 \r
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\n" ); document.write( "\n" ); document.write( "[1 2 -1 : 9]
\n" ); document.write( "[0 -1 1 : -3]
\n" ); document.write( "[0 1 -2 : 1] \r
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\n" ); document.write( "\n" ); document.write( "Now R3 + R2 gives us the final step\r
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\n" ); document.write( "\n" ); document.write( "[1 2 -1 : 9]
\n" ); document.write( "[0 -1 1 : -3]
\n" ); document.write( "[0 0 -1 : -2] \r
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\n" ); document.write( "\n" ); document.write( "From this the given system of equations reduces to: \r
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\n" ); document.write( "\n" ); document.write( "x + 2y - z = 9
\n" ); document.write( "-y + z = -3
\n" ); document.write( "-z = - 2\r
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\n" ); document.write( "\n" ); document.write( "Hence, the value of z can be directly found out. \r
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\n" ); document.write( "\n" ); document.write( "==> z = 2 \r
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\n" ); document.write( "\n" ); document.write( "now apply back substituion.\r
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\n" ); document.write( "\n" ); document.write( "-y + z = -3 \r
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\n" ); document.write( "\n" ); document.write( "-y + 2 = -3\r
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\n" ); document.write( "\n" ); document.write( "-y = -3 - 2\r
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\n" ); document.write( "\n" ); document.write( "-y = -5 \r
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\n" ); document.write( "\n" ); document.write( "==> y = 5 \r
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\n" ); document.write( "\n" ); document.write( "Using y and z in the first equation we find the value of x.\r
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\n" ); document.write( "\n" ); document.write( "x + 2y - z = 9 \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "x + 10 - 2 = 9\r
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\n" ); document.write( "\n" ); document.write( "x = 9 - 8 \r
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\n" ); document.write( "\n" ); document.write( "x = 1\r
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\n" ); document.write( "\n" ); document.write( "Hence, the solution.\r
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\n" ); document.write( "\n" ); document.write( "Now the second question. \r
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\n" ); document.write( "\n" ); document.write( "The given set of equations are: \r
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\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "x - y + z = 17\r
\n" ); document.write( "\n" ); document.write( "x + y - z = -11\r
\n" ); document.write( "\n" ); document.write( "x - y - z = 9 \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "This in the augmented form can be written as: \r
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\n" ); document.write( "\n" ); document.write( "[1 -1 1 : 17]
\n" ); document.write( "[1 1 -1 : -11]
\n" ); document.write( "[1 -1 -1 : 9]\r
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\n" ); document.write( "\n" ); document.write( "Lets perform the firts row operation that is R2 - R1 and R3- R1\r
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\n" ); document.write( "\n" ); document.write( "[1 -1 1 : 17]
\n" ); document.write( "[0 2 -2 : -28]
\n" ); document.write( "[0 0 -2 : -8]\r
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\n" ); document.write( "\n" ); document.write( "Now we divide R2/2 and R3/2 \r
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\n" ); document.write( "\n" ); document.write( "[1 -1 1 : 17]
\n" ); document.write( "[0 1 -1 : -14]
\n" ); document.write( "[0 0 -1 : -4]\r
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\n" ); document.write( "\n" ); document.write( "Thus the above augmented matrix can be written as: \r
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\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "x - y + z = 17 \r
\n" ); document.write( "\n" ); document.write( "y - z = -14 \r
\n" ); document.write( "\n" ); document.write( "-z = -4\r
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\n" ); document.write( "\n" ); document.write( "This implies z = 4 \r
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\n" ); document.write( "\n" ); document.write( "By back substitution, we find the values of y and x. \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "y - 4 = -14 \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "y = -14 + 4 \r
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\n" ); document.write( "\n" ); document.write( "==> y = -10 \r
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\n" ); document.write( "\n" ); document.write( "Now we find the value of x. \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "x - y + z = 17 \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "x + 10 + 4 = 17 \r
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\n" ); document.write( "\n" ); document.write( "x + 14 = 17 \r
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\n" ); document.write( "\n" ); document.write( "x = 17 - 14 \r
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\n" ); document.write( "\n" ); document.write( "x = 3 \r
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\n" ); document.write( "\n" ); document.write( "Hence, the solution.\r
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\n" ); document.write( "\n" ); document.write( "I hope all the stpes are quite clear..\r
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\n" ); document.write( "\n" ); document.write( "You can get back to me for an online help in math at any time of yours. \r
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\n" ); document.write( "\n" ); document.write( "Regards\r
\n" ); document.write( "\n" ); document.write( "Chitra\r
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