The method sqrt(double) is undefined for the type Main

出错代码

r2=(-b-sqrt(b*b-4*a*c))/2*a;

正确代码

r2=(-b-Math.sqrt(b*b-4*a*c))/2*a;

 

来源：https://www.cnblogs.com/zyz322/p/12283526.html