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daca x +3y=10 si 2y+5z =149 , determinați x +7y +10z

Răspuns :

2y+5z=149 ×2
4y+10z=298
×+3y=10. (x+3y)+(4y+10z)=308.


R:308
X+3Y=10
2Y+5Z=149
X+7Y+10Z=?

2Y+5Z=149  | *2

4Y+10Z=298
X+3Y=10
-------------------adunam cele doua ecuatii
X+7Y+10Z=308