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Calculati: 3a+5b+2c,daca a+b=15 si b+c=14

Răspuns :

3a+(2+3)b+2c=3a+2b+3b+2c=3(a+b)+2(b+c)=3*15+2*14=45+28=73




   
[tex]a+b=15 \\ b+c=14 \\ 3a+5b+2c= \\ = 3a+3b+2b+2c = \\ =3(a+b)+2(b+c)= \\ =3 \times 15 + 2 \times 14 = 45+28 = \boxed{73}[/tex]