Question

Determinati numerele rationale pozitive a,b,c stiind ca sunt direct proportional ,respectiv 2 ,3 ,5 si ab+bc+ca egal 775

Answer 1

a/2=b/3=c/5 => b=3a/2 , c=5a/2 => a*3a/2 + (3a/2)*(5a/2)+a*5a/2 = = (6*a^2+15*a^2+10*a^2)/4 => (31*a^2)/4=775 => 31*a^2=3100 => a^2=100 => a=10 => b=15 => c= 25