Question

cum se efectueaza marimile invers proportionale ??

3.Determinati numele a,b,c invers proportionale cu 2;4 si 8 stiind ca a+b+c=14

5.Determinati numele a,b si c invers proportionale cu numerele 2;4 si 5 daca suma lor este egala cu 19

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Answer 1

3)
2a=4b=8c = k
2a = k,a = k/2
4b = k,b = k/4
8c = k, c = k/8
a+b+c = 14
k/2+k/4+k/8 = 14
4k+2k+k = 112
7k = 112
k = 112:7
k = 16
a = k/2=16/2=8
b = k/4=16/4=4
c = k/8=16/8=2

5)
2a=4b=5c = k
2a = k,a = k/2
4b = k, b = k/4
5c = k, c = k/5
a+b+c = 19
k/2+k/4+k/5 = 19
10k+5k+4k=380
19k = 380
k = 380:19
k = 20
a = k/2=20/2=10
b = k/4 = 20/4 = 5
c = k/5 = 20/5 = 4