aflati numerele a,b,c stiind ca acestea sunt direct proportionale cu 5,7 si 8 si a+b+c=600
repede dau coroana


Răspuns :

{a,b,c} d.p. {5,7,8}

[tex]\frac{a}{5}=\frac{b}{7} = \frac{c}{8}[/tex] ⇒ a=5k, b=7k, c=8k

5k+7k+8k=20k

[tex]=>_{ipoteza}[/tex] 20k=600

=> k=600÷20

=> k=30

Daca k=30 =>

a= 5k= 30×5=150

b=7k=30×7=210

c=8k=30×8=240

Verificam : 150+210+240=600

Bafta!

Răspuns:

  • [tex]\boxed{\bf a=150}[/tex]
  • [tex]\boxed{\bf b=210}[/tex]
  • [tex]\boxed{\bf c=240}[/tex]

Explicație pas cu pas:

(*^_^*) Salutare!

[tex]\bf a+b+c=600[/tex]

[tex]\bf Fie~\{a,b,c\}~ d.p.~ \{5,7,8\}[/tex]

[tex]\bf \dfrac{a}{5} = \dfrac{b}{7} = \dfrac{c}{8}=k \implies[/tex]

[tex]\text{\it Notam valoarea comun a acestor rapoarte cu k (coeficient de proportionalitate)}[/tex]

[tex]\bf \dfrac{a}{5} =k \implies\bf a=5\cdot k[/tex]

[tex]\bf \dfrac{b}{7} =k \implies b=7\cdot k[/tex]

[tex]\bf \dfrac{c}{8}=k \implies c=8\cdot k[/tex]

[tex]\text{\it Inlocuim noile valori ale lui a,b,c in suma si vom avea:}[/tex]

[tex]\bf 5k+7k+8k=20k[/tex]

[tex]\bf 20k=600~~\bigg|:20[/tex]

[tex]\boxed{\bf k=30}[/tex]

[tex]\bf a = 5\cdot 30\implies \boxed{\bf a=150}[/tex]

[tex]\bf b = 7\cdot 30\implies \boxed{\bf b=210}[/tex]

[tex]\bf b = 8\cdot 30\implies \boxed{\bf c=240}[/tex]

[tex]\it Veificare:[/tex]

[tex]\it 150+210+240 = 600~(adevarat)[/tex]

==pav38==