SOLUTION: Determine the value of (x + y + z) if, 3x � 2y � 3z = -1 6x + y + 2z = 7 9x + 3y + 4z = 9

Question 256815: Determine the value of (x + y + z) if,
3x � 2y � 3z = -1
6x + y + 2z = 7
9x + 3y + 4z = 9
Found 2 solutions by drk, stanbon:
Answer by drk(1908) (Show Source): You can put this solution on YOUR website!
Here are the equations:
(i) 3x � 2y � 3z = -1
(ii)
(iii)
step 1 - It may be easier to get rid of the y's first. We want to multiply by easy numbers. Multiply (ii) by 2 and add to (i) to get
(iv) 3x � 2y � 3z = -1
(v)
and then
(vi)
step 2 - multiply (ii) by -3 and add to (iii) to get
(vii)
(viii)
and then
(ix)
Now, multiply (vi) by 2 and add to (ix) to get
(x)
(xi)
(xii)

Since x = 2/3, we sub that back into (x) to get

Now put those both back into (i) to get

So we finally have {2/3, -3, 3}
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
Determine the value of (x + y + z) if,
3x � 2y � 3z = -1
6x + y + 2z = 7
9x + 3y + 4z = 9
----------------------------
I used a calculator matrix function to get:
x = 2/3
y = -3
z = -3
--------
x + y + z = 2/3
================
Cheers,
Stan H.
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