Question

1))) numerele a si b sunt invers proportionale cu 0,2 si 0,5
a) calculati valuarea raportului a/b
b)daca a=b+3,atunci aflati valuarea lui b.
2) a)numerele a+3,b+4,c+5 sunt direct proportionale cu 3,4,5.aflati numerele a,b si c daca a+b+c=60
b) numerele a si b sunt direct proportionale cu 4 si 5iar numerele b si c sunt invers proportionale cu 5 si 4 . Aflati numerele a ,b si c daca a+b+c=61
dau COROANA

Answer 1

Am anexat o rezolvare !

Answer 2

$\it 0,2=\dfrac{\ \ 2^{(2}}{10} =\dfrac{1}{5} \\ \\ \\ 0,5=\dfrac{\ \ 5^{(5}}{10} =\dfrac{1}{2} \\ \\ \\ \{a,\ \ b\}\ i.\ p.\ \left\{\dfrac{1}{5},\ \ \dfrac{1}{2} \right\} \Rightarrow \{a,\ \ b\}\ d.\ p. \ \{5,\ \ 2\} \Rightarrow \dfrac{a}{5} =\dfrac{b}{2} \Rightarrow\dfrac{a}{b} =\dfrac{5}{2} \Rightarrow \\ \\ \\ \Rightarrow \dfrac{a}{b} =2,5 \Rightarrow a > b\ de\ 2,5\ ori$

$\it b)\ \ a=b+3 \ \ \ \ \ (*) \\ \\ \dfrac{a}{b} =\dfrac{5}{2} \ \stackrel{(*)}{\Longrightarrow} \ \dfrac{b+3}{b} =\dfrac{5}{2} \Rightarrow \dfrac{b+3-b}{b} =\dfrac{5-2}{2} \Rightarrow \dfrac{3}{b} = \dfrac{3}{2} \Rightarrow b=2$