solve the system of equations in 3 variables !!
x+y-z=-1
x+y+z=3
3x-2y-z=-4

Question

solve the system of equations in 3 variables !!
x+y-z=-1
x+y+z=3
3x-2y-z=-4

anonymous · Answer

This one is easy enough to solve with substitution, but if you're feeling lazy, try a matrix and reduced-row echelon form.

anonymous · Answer

how do I do it ? @CliffSedge

anonymous · Answer

For extra-laziness you can use a graphing calculator that has matrix operations, but you'll probably learn more doing it by hand.

I think the easiest place to start would be with the first two equations. Adding them together, the variable z is eliminated. You can then solve that system for x and y. Once you have x and y, you can substitute them into any of the equations to solve for z.

anonymous · Answer

Though, now that I look at it more carefully, it looks like the system is inconsistent. I don't think it has a unique solution.

anonymous · Answer

No, never mind - thought I saw something else.

anonymous · Answer

Ok, here's a plan: Add equations 1 and 2 to eliminate z. Solve that resulting equation for y and substitute that into equation 3. That will give you an equation with only x and z. Subtract equations 1 and 2 to get a value for z. Use that to get x, and then you can get y.