Question

suma a trei numere este 120. Aflati numere stiind ca sunt direct proportionale cu 5, 12 si 13

Answer 1

Răspuns:

a)

a+b+c=120

a/2=b/3=c/5    b=3a/2    c=5a/2

a+3a/2+5a/2=120

2a+3a+5a=240

10a=240

a=24

b=3*24/2=36

c=5*24/2=60

b)

a+b+c=120

a/3=b/5=c/7    b=5a/3    c=7a/3

a+5a/3+7a/3=120

3a+5a+7a=360

15a=360

a=24

b=5*24/3=40

c=7*24/3=56

Explicație pas cu pas:

Answer 2

Răspuns:

a/5=b/12=c/13=k→ coeficient de proportionalitate

a=5k

b=12k

c=13k

a+b+c=120=>5k+12k+13k=120

30k=120=>k=120:30=>k=4

a=5·4=>a=20

b=12·4=>b=48

c=13·4=>c=52