Răspuns :
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 )
______________________________
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 )
______________________________
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