Question

Numerele x+2009 , y+2010 , z+2011 sunt direct proportionale cu 7; 7,5 respectiv 8. Aflati x, y si z stiind ca y este media aritmetica dintre x si z , iar x+y+z=720.
VA ROOOOGGGGGG! E URGENT.
E PENTRU MAINE.
PLS. PLEASE.

Answer 1

×+2009supra7 = y+2010supra7,5 = z+2011supra8=k => x=7k-2009 , y=7,5k-2010 , z=8k-2011 x+y+z=720 => 7k-2009+7,5k-2010+8k-2011=720 22,5k-6030=720 22,5k=720+6030 22,5k=6750 k=6750×10supra225 (simplifici 6750 si 225 prin 225 si ramane sus 30 si jos 1) => k=300 => x=7×300-2001 => x=2100-2009 => x=91 => y=7,5×300-2010 => y=2250-2010 => y=240 => z= 8×300-2011 => z=2400-2011 => z=389 Verificare: ma(x,z)=ma(91,389) => ma(91,389)=91+389supra2 ma(91,388)=480supra2 ma(91,388)=240=y