Question

numerele rationale pozitive a,b si c sunt direct proportionale cu 3,7 si 8, iar 8a+7b+3c=485

Answer 1

{a,b,c}d.p{3,7,8}  8a+7b+3c=485
a/3=b/7=c/8=k
a=3k
b=7k   } ⇒8*3k+7*7k+3*8k=485
c=8k         24k+49k+24k=485
                 97k=485/:97
                 k=5
⇒a=3*5=15
⇒b=7*5=35
⇒c=8*5=40