北京动物咖啡厅:分式的加减

来源:百度文库 编辑:高考问答 时间:2024/04/29 11:49:08
已知:x/y+z=a, y/x+z=b, z/x+y=c,试求a/a+1 + b/b+1 + c/c+1 的值

把a=x/(y+z),b=y/(z+x),c=z/(x+y)
代到 a/(a+1)+b/(b+1)+c/(c+1)
得 [x/(y+z)]/[1+x/(y+z)]+[y/(z+x)]/[1+y/(z+x)]+[z/(x+y)]/[1+z/(x+y)]=[x/(y+z)]/[(x+y+z)/(y+z)]+[y/(z+x)]/[(x+y+z)/(z+x)]+[z/(x+y)]/[(x+y+z)/(x+y)]=x/(x+y+z)+y/(x+y+z)+z/(x+y+z)=(x+y+z)/(x+y+z)=1