👤

Daca a+b=7 iar b+c=10 aflati a+3b+2c

Răspuns :

a+b=7
b+c=10  inmultim cu 2    2b+2c=20
a+b+2b+2c=7+20
a+3b+2c=27

[tex]a+b=7 \\ b+c=10~~|*2 \\ 2b+2c=20 \\ a+b+2b+2c=7+20 \\ a+3b+2c=27[/tex]