Help this Metlab plz

EXERCISE 2 Recall that a geometric sum is a sum of the form a + ar + ar+ ar3 + .... (a) Write a function file called geomsum1 which accepts the values of r, a and n (in that order) as input arguments and uses a for loop to return the sum of the first n terms of the geometric series. Test your function for r = -2/7, a = 6, n = 11. (b) Write a function file called geomsum2 which accepts the values of r, a and n (in that order) as input arguments and uses the built in command sum to find the sum of the first n terms of the geometric series. Test your function for r = -2/7, a = 6, n = 11. Hint: Start by defining the vector e = [O:n-1) and then evaluate the vector R = r. e. It should be easy to figure out how to find the sum from there