Question

Dacă a+b=11 b+c=14si c+a =13 calculați a)a+b+c;b)2a+2b+2c;c)3c+5b+2c;d)ab+ac+10.

Answer 1

adunam relatiile
a+b+b+c+c+a=38
2(a+b+c)=38
a+b+c=19 (rel.1)

2(a+b+c)=19x2=38

5(b+c)=5x14=70

a=19-14 a=5(din rel.1)
a(b+c)+10=5*14+10=80