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Question 60688This question is from textbook Algebra & Trigonometry
: x+3=0
x+y+z=1
3x-y-z=11
We must use the Gauss-Jordan elimination.
I have already tried the problem with others and i keep getting the same wrong answer. the book says the answer is (3,-1,-1).
I did this:
1 3 0 / 0
1 1 1 / 1
3 -1 -1 / 11
then i did multiplied -1 to the first row and added to the second row. then multiplied -3 to the first row and added the product to the third row which gave me
1 3 0 / 0
0 -2 1 / 1
0 -10 -1 / 11
i then multiplied -1/2 to the second row which gives me
1 3 0 / 0
0 1 -1/2 / -1/2
0 -10 -1 / 11
them i multiplied 10 to the second row and added the product to the third row and got
1 3 0 / 0
0 1 -1/2 / -1/2
0 0 -6 / 16
by multiplying -1/6 to the third row gave me
1 3 0 / 0
0 1 -1/2 / -1/2
0 0 1 / -16/6
then i multiplied 1/2 to row 3 and added it to row 2 giving me
1 3 0 / 0
0 1 0 / -4/3
0 0 -6 / -16/6
then by multiplying -3 to the row 2 and adding that to row 1 i got
1 0 0 / 4
0 1 0 / -4/3
0 0 1 / -16/6
this give me the answer (4,-4/3,-16/6) which is clearly wrong. Could you look over my steps to see what i did wrong please?
This question is from textbook Algebra & Trigonometry
Answer by hayek(51)   (Show Source):
You can put this solution on YOUR website! If the first equation is x+3y=0, then your error is in this step:
them i multiplied 10 to the second row and added the product to the third row and got
1 3 0 / 0
0 1 -1/2 / -1/2
0 0 -6 / 16
The last number should be 11-5=6, not 16.
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