[v0id]

A very simple example, showing how "Derived" inherits the functionality from "Base".

#include <iostream>

class Base
{
    public:
        void basefunction() { std::cout << "In Base" << std::endl; }
};

class Derived : public Base
{
    public:
        void derivedfunction() { std::cout << "In Derived" << std::endl; }
};

int main()
{
    Base b;
    Derived d;
    
    b.basefunction();
    d.basefunction();
    d.derivedfunction();
        
    return 0;
}

I don't know what you mean by that formula, could you be more specific?