Ex 5/ testul 2
X +4y+2z=13
3x+2z=11
X+y+z=?

x + 4·y + 2·z = 13
3·x + 2·z = 11
Aduni cele doua ecuatii.
x + 4·y + 2·z + 3·x + 2·z = 13 + 11
4·x + 4·y + 4·z = 24 | : 4
x + y + z = 6