Posted by **Lilly** on Thursday, November 3, 2011 at 12:04am.

1. Solve for x, y, z in the following system:

2x-3y-2=z

y-x+z=1

-y-2z=7

The answers are: x=-7 y=-5 and z=-1 however I don't know how to go about this.

- Math-System of Equations -
**Reiny**, Thursday, November 3, 2011 at 8:28am
From the 3rd: y = -2z-7

in the 1st:

2x - 3(-2z-7) - z = 2

2x +6z +21 - z = 2

2x + 5z = -19 (#4)

in the 2nd:

-2z - 7 - x + z = 1

x + z = -8

2x + 2z = -16 (#5)

#4 - #5 :

3z = -3

z = -1

sub into y = -2z-7 ---> 2-7 = -5

sub into 2nd:

-5 - x - 1 = 1

-x = 7

x = -7

so , x = -7, y = -5 and z = -1

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