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determinati nunerele a,b si c invers proportionale cu numerele 2;4 si 5 daca suma lor este egala cu:
a)19
b)57
c)76
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Răspuns :

Renatemambouko
2a=4b=5c   b=2a/4=a/2   c=2a/5
a+b+c=19
a+a/2+2a/5=19
10a+5a+4a=190
19a=190
a=10
b=10/2=5
c=2*10/5

a+b+c=57
a+a/2+2a/5=57
10a+5a+4a=570
19a=570
a=30
b=30/2=15
c=2*30/5=12

a+b+c=76
a+a/2+2a/5=76
10a+5a+4a=760
19a=760
a=40
b=40/2=20
c=2*40/5=16
Orhideea12345678
a*2=b*4=c*5= K
a) a=K/2
    b=K/4
    c=K/5
a+b+c= 19
K/2+ K/4+ K/5=19
K/2*10+K/4*5+ K/5*4=19*20
10K+4K+5K=380
19K=380
K=20
 a=20/2=10
 b=20/4=5
 c=20/5=4

b)  a=K/2
    b=K/4
    c=K/5
 a+b+c=57
K/2+ K/4+ K/5=57
K/2*10+K/4*5+ K/5*4=57*20
10K+4K+5K=1140
19K=1140
K=60

a=60/2=30
b=60/4=15
c=60/5=12

c)a=K/2
    b=K/4
    c=K/5
 K/2+ K/4+ K/5=76
K/2*10+K/4*5+ K/5*4=76*20
10K+4K+5K=1520
19K=1520
K=80

a=80/2=40
b=80/4=20
c=80/5=16