# How did my professor do this?

I'm trying to figure out how my professor got to the step circled in red in the image below:

How did he get the values of the first row to become completely positive, and how did he derive the values of the entire 2nd row?

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The second entry in the first row is -1, that's probably a typo of your professor. For the second row, he did a row operation by row 2 -> row 2 - h times row 1. – user27126 Feb 26 '13 at 6:24
Perhaps has trouble with minus signs. I certainly do. – André Nicolas Feb 26 '13 at 6:26
And for the other encircling: "which values" would be prefered? – Hagen von Eitzen Feb 26 '13 at 7:46

The entry in the first row and second column was misprinted as $1$ when it should be $-1$. The change to the second row is a standard row operation, replacing row 2 with row 2 minus $h$ times row 1.