Question

Determinati nr a ,b ,c stiind ca a\3=b\7=c\3 si2a+5b-4c=108

Answer 1

a/3 = b/7 = c/3
a = 3b/7
c = 3b/7
2a+5b-4c = 108
inlocuim in functie de b
2×3b/7 + 5b- 4×3b/7 = 108 /×7
6b + 5b - 12b = 756
29b =756
b = 756/29
a = 3×756/7×29 = 2268/203
c = 2268/203

verificare:
2×2268/203+5×756/29 -4×2268/203 =
= 4536/203+3780/29-9072/203 =
= (4536+7×3780-9072)/203 =
= (4536+26460-9072)/203 =
= 21924/203 =
= 108