Question

Determinati numerele raționale pozitive x, y, z care sunt invers
proportionale cu numerele 3,5 si 6, iar x*y + x*y +y*z= 560.​

Answer 1

Răspuns:
x/(1/5)=k=>x=k/5
y/(1/6)=k=>y=k/6
z/(1/10)=k=> z=k/10
5x+4y-8z=520
5·k/5+4·k/6-8·k/10=520
k+2k/3-4k/5=520 aducem la acelasi numitor
15k+10k-12k=7800
13k=7800
k=600
x=k/5=>x=600:5=120
y=k/6=>y=600:6=100
z=k/10=>z=600:10=60