Originally Posted by

**Adrian** Solve the following system, where a, b, and c are constants:

x1 + x2 + x3 = a

2x1 + 2x3 = b

3x2 + 3x3 = c

If I put this into a matrix I get:

1 1 1 | a

2 0 2 | b

0 3 3 | c

I'm really not sure where to go from here because it seems to me like row 2 and 3 will cancel out making b and c equal 0, but I'm not really experienced with this and I'm not even sure what I'm trying to obtain in the end.

Thanks

subtract twice row 1 from row 2:

Code:

1 1 1 | a
0 -2 0 | b-2a
0 3 3 | c

Now add 3/2 times row 2 to row 3:

Code:

1 1 1 | a
0 -2 0 | b-a
0 0 3 | c + (3/2)(b-2a)

Now solve by back substitution.

RonL