Question

Dacă a+b=1450, b+c=1231, iar a+c=2242, află dublul sumei celor trei numere.

Answer 1

a + b = 1450

b + c = 1231

a + c = 2242
____________ adunam cele 3 relatii

2 × a + 2 × b + 2 × c = 1450 + 1231 + 2242

2 × ( a + b + c ) = 4 923 (dublul sumei )
______________________________

Answer 2

a + b       = 1 450

     b + c = 1 231

a   +      c = 2 242

_______________ → adun sumele date

2 × a + 2 × b + 2 × c = 1 450 + 1 231 + 2 242

2 × ( a + b + c ) = 4 923 → dublul sumei