a. Write a function sum() that takes as parameter an integer N and returns a float value equal to the following sum: N 5n + 1 2n2 + 3 n=0 Write the prototype and the definition of the function. b. Write a C++ program that asks the user to enter an integer and uses the function sum() to print on the screen the value of 5n+1 2n2+3 n=0 Sample run: Please enter the value of N: 12 Sum = 6.44