Systems of equations & equalities

[barto]

5 x + 2y =4
3x + 4y + 2z =6
7x + 3y + 4z =29

I've worked it, and worked it, and whenever I check my answer, it never fits with the problem.

I had x = 1.56
y = -207/109
z = 4.46

This is driving me crazy. Thaks for your help.

 

[stapel]

I've worked it, and worked it, and....

What method are you using? What were your steps?

Thank you.

Eliz.

 

[barto]

I'm using process of elimination. Do you know how to do this?

 

[stapel]

I'm using process of elimination. Do you know how to do this?

Yeah.... But I try to avoid it for systems with more than two variables though; it can get awfully messy.... :shock:

There isn't just one "right" way, of course. One set of steps might be as follows:

1) Multiply the second row by "2". Subtract this from the third row. The first and third rows now have only x and y.

2) Solve this subsystem: Multiply the third row by "5", and subtract the third row from the first. Solve the result for y. Back-solve for x.

3) Plug the values of x and y into either of the second or third (original) rows, and solve for z.

Eliz.

 

[barto]

Thanks, Eliz...I'll try it now! It's my last problem of the night and it's got to work.