x/(120-x)=(60-x)/60

问题描述:

x/(120-x)=(60-x)/60

两边都乘以 60(120-x)(x≠120) 60x=(60-x)(120-x)60x=7200-180x+x²x²-240x+7200=0(x-120)²=14400-7200 =7200x-120=±√7200=±60√2x=120±60√2