SOLUTION: Using the matrices find a general solution 2x-y+3z=5 -x+4y+4z=-1 if you could show how you did this I would really appreciate it. ty

Algebra ->  Matrices-and-determiminant -> SOLUTION: Using the matrices find a general solution 2x-y+3z=5 -x+4y+4z=-1 if you could show how you did this I would really appreciate it. ty      Log On


   



Question 626268: Using the matrices find a general solution
2x-y+3z=5
-x+4y+4z=-1
if you could show how you did this I would really appreciate it. ty

Answer by Edwin McCravy(20086) About Me  (Show Source):
You can put this solution on YOUR website!
Using the matrices find a general solution
system%282x-1y%2B3z=5%2C%0D%0A+-1x%2B4y%2B4z=-1%29

Convert to this matrix:



We want to use row operations to get it looking like this: 

First we get the two zeros:

To get a 0 where the -1 is on the bottom left, multiply
the second row by 2



and add the first row to the 2nd row



To get a 0 where the remaining -1 is on the first row, multiply
the first row by 7



and add the second row to the first row:



Now we get the two 1's

Divide the first row through by 14, and the second row
through by 7



and reduce:



convert back to a system of equations:



or

system%28%0D%0Ax=19%2F7-expr%2816%2F7%29z%2C%0D%0Ay=3%2F7-expr%2811%2F7%29z%29

Solution: choose any value k for z then annex z=k to the system:

system%28%0D%0Ax=19%2F7-expr%2816%2F7%29k%2C%0D%0Ay=3%2F7-expr%2811%2F7%29k%2Cz=k%29

or

(x,y,z) = (19%2F7-expr%2816%2F7%29k,3%2F7-expr%2811%2F7%29k,k)

Edwin