Please help solve problem #2 with detailed steps, for MATLAB, thank you

Problem 1: Write a function with the header: function backDiff calcBackwardDiff (x, y) The function should take two 1D array inputs where x is the independent variable and y is the dependent variable. The function should return a 1D array containing the derivative at each point calculated using the backward difference approximation. Do not use the "diff function. Problem 2: Write a function with the header: function sumArea leftRiemann (xVals, yVals, a,b The function should take two 1D array inputs where xVals is the independent variable and yVals is the dependent variable. The function should return the integral from the interval [a,b] calculated using the left Riemann sum method. Problem 3: Write a function with the header: function B myEvenArray (A) The function should take a 1D input array and return a 1D array where all numbers are made even by adding 1 to every odd number in the input array