Question

Soe
x+y-2z=5
-x+2y+z=2
2x+3y-z=9

Answer 1

x=1

y=2

z=-1

Explanation:

Add the first two equations: (this will be equation 4)

`3y - z = 7`

Multiply the first equation by 2:

`2x + 2y - 4z = 10`

Take the third equation and subtract the above equation.

`y + 3z = - 1`

Multiply that by 3:

`3y + 9z = - 3`

Subtract equation 4:

`10z = - 10`

`z = - 1`

For y+3z=-1, plug in values:

`y + 3( - 1) = - 1`

`y - 3 = - 1`

`y = 2`

Plug in y and z values in first equation:

`x + 2 - 2( - 1) = 5`

`x + 2 + 2 = 5`

`x = 1`