Question

Determinati numerele rationale pozitive x,y,z care sunt invers proportionale cu numerele 5,6,10, iar 5x+4y-8z=520
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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