Question

Solve the following system of equations using elimination:

x+y+z=3
x-y+2z=-1
4x+y+z=15

Answer 1

well start by reducing the problem to 2 equations with 2 unknowns

add the 1st and 2nd equations to eliminate y

x + y + z = 3
x -y + 2z = -1
-------------------
2x +3z = 2

next add the 2nd and 3rd equations to eliminate y

x - y + 2z = -1
4x + y + z = 15
-----------------
5x +3z = 14

so you now have 2 equation in 2 unknowns

2x + 3z = 2
5x + 3z = 14


subtract the 2nd equation from the 1st..

2x + 3z = 2
- 5x + 3x = 14
-------------------
-3x = -12

now solve for x

substitute x into either of the equations above to find z

then substitute your values for x and z into any of the original equations to find y.

hope this helps

Answer 2

am i substituting x into one of the original three equations?