Question 1002469: 3x+2y-8z=29
9x-y+2z=23
-x-2y+8z=-11
Answer by mananth(16946)   (Show Source):
You can put this solution on YOUR website! 3 x + 2 y + -8 z = 29 -------------- 1
9 x + -1 y 2 z = 23 -------------- 2
-1 x + -2 y + 8 z -11 -------------- 3
consider equation 1 &2 Eliminate y
Multiply 1 by 1 -5
Multiply 2 by 2 4
we get
3 x + 2 y + -8 z = 29
18 x + -2 y + 4 z = 46
Add the two
21 x + 0 y + -4 z = 75 ------------- 4
consider equation 2 & 3 Eliminate y
Multiply 2 by -2
Multiply 3 by 1
we get
-18 x + 2 y + -4 z = -46
-1 x + -2 y + 8 z = -11
Add the two
-19 x + 0 y + 4 z = -57 -------------5 5
Consider (4) & (5) Eliminate x
Multiply 4 by 19
Multiply (5) by 21
we get
399 x + -76 z = 1425
-399 x + 84 z = -1197
Add the two
0 x + 8 z = 228
/ 8
z = 28.50
Plug the value of z in (5)
-19 x + 4 z = -57
-19 x = -171
x = 9
plug value of x & z in 1
27 + 2 y + -228 = 29
2 y = 29 + -27 + 228
y = 115
x= 9.00 ,y= 115.00 ,z= 28.50
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