(1 point) The monthly payment for a home loan is given by a function f(P, r, M) where P is the principal (the initial size of the loan), r the interest rate, and /V the length of the loan in months. Interest rates are expressed as a decimal: A % interest rate is denoted by r = 0.045. If P = 400000, r = 0.045, and N = 204(a 17-year loan), then the monthly payment is f(400000, 0.045, 204) = 602. Furthermore, with these values we have of of = 0.0065, of - = 5425, = -1.7455 ap ar ON Estimate: (a) The change in monthly payment per 2000 increase in loan principal: Af ~ dollars (b) The change in monthly payment if the interest rate changes from r = 0.045 to r = 0.04: Af ~ dollars (c) The change in monthly payment if the length of the loan changes from 17 to 20 years: Af ~ dollars