Question

Sa se afle numerele x si y stiind ca sunt invers proportionale cu 0 (3) si 0,25 si ca x.y=300

Answer 1

0,(3)=3/9=1/3
0,25=25/100=1/4
x/1/3=3x
y/1/4=4y
=>3x=4y=>x=4y/3
xy=300=>4ypatrat/3=300
4ypatrat=900
ypatrat=225=>y=15
x=300:15=>x=20

Answer 2

0,(3)=3/9=1/3  si  0,25=25/100=1/4 
daca (x;y) i.p. (1/3;1/4)
adica: $\frac{x}{ \frac{1}{ \frac{1}{3} } } = \frac{x}{ \frac{1}{ \frac{1}{4} } }\;\leftrightarrow\;\frac{x}{3}=\frac{y}{4}=k$[tex]x=3k\;si\;y=4k\;\\ x*y=12k^2=300\;\;deci\;\;k=5[/tex]

x=15  si  y=20