Question

Dacă a+b= 1.450, b+c= 1.231, iar a+c= 2.242, află dublul sumei celor trei numere.

Answer 1

a+b= 1.450 ⇒ a=1450-b
b+c= 1.231 ⇒ c=1231-b
a+c= 2.242 ⇒ 1450-b+1231-b=2.242⇒2b=2.681-2.242⇒ b=439÷2=219,5
a=1.450-b=1.450-219,5=1.230,5
c=1.231-b=1.231-219,5=1.011,5
2·(1.230,5+219,5+1.011,5)=2·.2461,5=4.923

Answer 2

a + b = 1 450
b + c = 1 231
a + c = 2 242
adunand cele 3 relatii,aflam chiar dublul sumei celor 3 numere:

a + b + b + c + a + c = 1 450+1 231 + 2 242
2 × a + 2 × b + 2 × c = 4 923
2 × (a + b + c ) = 4 923