Borland C++ Excersise help.

[Moren]

Edit: My first problem is solved, I just need 1 more thing, I need to solve a cube and fourth root, but I don't know how

#include <iostream.h>
#include <conio.h>
#include <math.h>

float a,s,c,f;
void main()
{
    cout<<"Add a number";
   cin>>a;
   s= sqrt(a);
   c= ???
   f= ???
   cout<<"The square root is: "<<s<<endl;
   cout<<"The cubic root is: "<<c<<endl;
   cout<<"The fourth root is: "<<f<<endl;
   getch();
}