Edward C. answered • 02/23/15
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Pivoting about the element in row 2, column 1 means that you want to use row reduction techniques to make the rest of the elements in column 1 equal to 0.
If you multiply row 2 by (7/4) and then add the result to row 1 the -7 in row 1, column 1 will become 0.
So Row 2 = [ 4 -10 | 6 ]
(7/4) * Row 2 = [ 7 (-35/2) | (21/2) ]
Row 1 = [ -7 -4 | -4 ]
Adding these together gives
[0 (-43/2) | (13/2) ]
which is the new Row 1 after the pivot
[ 0 (-43/2) | (13/2) ]
[ 4 -10 | 6 ]
Edward C.
tutor
The row that contains the element you are pivoting about doesn't change, so row 2 remains the same.
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02/23/15
Lanesha W.
The first row was correct but it says the second row was wrong, the first number on the new second row is 1.
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02/23/15
Edward C.
tutor
Well, you can divide the second row by 4 to force the pivot element to be 1, so you would get
[1 (-5/2) | (3/2) ]
I guess it depends on what your definition of pivoting is.
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02/23/15
Lanesha W.
02/23/15