Aflati numerele a, b si c stiind ca sunt direct proporționale cu 2,3 si 5 iar 3a+2b+c=34

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a / 2 = b / 3 = c / 5 = k ⇒ a = 2 k; b = 3 k; c = 5 k

3 a + 2 b + c = 34

3 × 2 k + 2 × 3 k + 5 k = 34

6 k + 6 k + 5 k = 34

17 k = 34

k = 34 : 17

k = 2

a = 2 × 2 = 4

b = 3 × 2 = 6

c = 5 × 2 = 10

Verific: 3 × 4 + 2 × 6 + 10 = 12 + 12 + 10 = 34

Raspuns: a = 4; b = 6; c = 10