Solving Simultaneous Equations for Homework Assignments

[JFonseka]

Homework Statement

It's been a while since I solved these kind of things. I can only remember how to solve 2 simultaneous equations

40x + 40y = 10
-40y -40z = -2
40x - 40z = 8

Homework Equations

None

The Attempt at a Solution

Just need a pointer on what method to use.

 

[CompuChip]

You can put them in a matrix or row-reduce. But since the coefficients are very much alike, you can also try to do it more efficiently.
For example, you can use the latter two to eliminate z and then solve the remaining system of two. Then plug the solutions back into either of the last ones, and find z.

 

[meganw]

1) Divide all by 40. (This should simplify a lot)
2) Solve for y in terms of x (first equation)
3) Plug in for y (from equation 1) in the second equation, and solve for x. (Your y is in terms of x, so this should be easy)
4) Now, plug in the x that you found in the second equation (in terms of z), into the last equation. You'll find z. From there it's easy.

And of course, this is just one of the many ways to do it in this method.

 

[physixguru]

Use cross multiplication method.