Question

a+b+c, daca 2a+3b+4c =7, iar 7a+5b+3c=8

Answer 1

2a+3b+4c=7/·(-7)
7a+5b+3c=8/·2

Formam sistem:

-14a-21b-28c=-49
14a+10b+6c=16

Se reduce -14a cu 14a:

-21b-28c=-49/·3
10b+6c=16/·14


-63b-84c=-147
140b+84c=224

Se reduce -84c cu 84c:

-63b=-147
140b=224

77b=77
b=1.

140b+84c=224
140+84c=224
84c=84
c=1

14a+10b+6c=16
14a+16=16
a=1.

a+b+c=3.

Sunt sigura ca am gresit undeva, asa ca te-as ruga sa te uiti la indicatii si raspunsuri.