SOLUTION: How do i solve this to get three variables? a+b+c=3 3b-c=4 2a-b-2c=-5

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Question 234161: How do i solve this to get three variables?

a+b+c=3
3b-c=4
2a-b-2c=-5
Found 2 solutions by nyc_function, solver91311:
Answer by nyc_function(2741) About Me  (Show Source):
You can put this solution on YOUR website!
Use matrices to solve.
If you want to learn how to solve this using matrices, visit the link below.
http://mathtv.com/

Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!







I don't know how you do it. But I would use the substitution method on this one.

Solve the 2nd equation for :



Substitute this expression for into the first equation:



and then simplify:



Solve this one for :



Substitute this expression for and the previously derived expression for into the third equation:

.

And then solve for







Substitute this value for the derived expression for and solve for . Substitute the values for and into the original first equation and solve for . The last couple of steps are left as an exercise for the student.

John