how can I use exponent function

Answer 1

I think you cant use exponential function. But you can use power function by introducing math header file. For eg pow(value, its power)

Answer 2

This is what I do;
#include <iostream>
using namespace std;
#define _USE_MATH_DEFINES
#include <cmath>

Then use pow(x, y) with x being the value and y being the power.
It always works for me