Question

Andra si Raluca au fiecare sume de bani proportionale cu numerele 4 si 5. Media geometrica a sumelor de bani a celor doua fete este 24 radical din 5. Cati lei are fiecare? Mergand printr-un magazin fetele vor sa-si cumpere cate un tricou pe care scrie "99lei-55%reducere". Le ajung banii?

Answer 1

x-Andra
y-Raluca

√x*√y=24√5
4x=5y

√x*√y=24√5
y=4/5x

√x*√4/5x=24√5
y=4/5x

√x*4/5x=24√5
y=4/5x

√4/5x²=24√5
y=4/5x

4x²/5=576*5
y=4/5x

4x²/5=2880
y=4/5x

4x²=2880*5
y=4/5x

4x²=14400
y=4/5x

x²=14400/4
y=4/5x

x²=3600
y=4/5x

x=√3600
y=4/5x

x=60
y=4/5*60

x=60 lei are Andra;
y=48 lei are Raluca.

99/100*55%=54,54 lei,deci doar Andra isi poate cumpara un tricou.
Bafta!