2x + 3y + z = 15350 3x + y + 2z = 15850 x + 2y + 3z = 12300 Maka, x + y + z = ?

Jumlahkan semua persamaan.
[tex]2x+3y+z=15.350\\ 3x+y+2z=15.850\\ x+2y+3z=12.300\\ --------------+\\ 6x+6y+6z=43.500\\ 6(x+y+z)=43.500\\ x+y+z=7.250[/tex]

2x + 3y + z = 15.350  (x2)
3x + y + 2z = 15.850  (x1)
-----------------------------------
4x + 6y + 2z = 30.700
3x + y + 2z = 15.850
------------------------------- -
x + 5y = 14.850

2x + 3y + z = 15.350   (x3)
x + 2y + 3z = 12.300    (x1)
-------------------------------------
6x + 9y + 3z = 46.050
x + 2y + 3z = 12.300
---------------------------------- -
5x + 7y = 33.750

x + 5y = 14.850   (x5)
5x + 7y = 33.750 (x1)
-----------------------------
5x + 25y = 74.250
5x + 7y = 33.750
------------------------------ -
18y = 40.500
y = 40.500 / 18
y = 2.250

x + 5y = 14.850
x + 5(2.250) = 14.850
x + 11.250 = 14.850
x = 14.850 - 11.250
x = 3.600

2x + 3y + z = 15.350
2(3.600) + 3(2.250) + z = 15.350
7.200 + 6.750 + z = 15.350
13.950 + z = 15.350
z = 15.350 - 13.950
z = 1.400

maka
x + y + z = 3.600 + 2.250 + 1.400 = 7.250