Question

Aflati x,y,z care sunt invers proportionale cu 3,4,7 iar x+y+z=61

Answer 1

x·3=y·4=z·7=k
⇒x·3=k⇒x=k/3;
⇒y·4=k⇒y=k/4;
⇒z·7=k⇒z=k/7;
⇒x+y+z=61
⇒k/3+k/4+k/7=61
⇒28k/84+21k/84+12k/84=61
⇒61k/84=61
⇒61k=84·61
⇒61k=5124
⇒k=84;
⇒x=84/3⇒x=28;
⇒y=84/4⇒y=21;
⇒z=84/7⇒z=12;