SOLUTION: QUESTION # 8 SOLVE BY THE ADITION METHOD: x-5y-z=-5 2x-2y+z=-11 -x+2y-2z=11

Question 216615: QUESTION # 8
SOLVE BY THE ADITION METHOD:
x-5y-z=-5
2x-2y+z=-11
-x+2y-2z=11
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
SOLVE BY THE ADDITION METHOD:
x - 5y - z=-5
2x- 2y + z=-11
-x+ 2y -2z= 11
:
Multiply the 1st equation by -1 and add
-x + 5y + z=+5
2x- 2y + z=-11
-x+ 2y -2z= 11
-------------------Addition eliminates x and z
0x + 5y +0z = 5
y =
y = 1
;
use the 1st two equations, replace y with 1 and add
x - 5 - z=-5
2x- 2 + z=-11
:
x - z =-5 + 5
2x+ z=-11 + 2
:
x - z = 0
2x+ z =-9
---------------addition eliminates z
3x = -9
x =
x = -3
:
Use 2x + z = -9; replace x with -3
2(-3) + z = - 9
-6 + z = -9
z = -9 + 6
z = -3
:
x = -3; y = 1; z = -3
;
;
Check solutions in 3rd original equation
-x + 2y -2z = 11
-(-3) + 2(1) - 2(-3) = 11
+3 + 2 + 6 = 11
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