(c) We would like to approximate a differentiable function f at y using a linear function Ly(x) := ax+b. We set a and b so that f and Ly have the same value and the same derivative at y (i.e., Ly(y) = f(y) and L'y(y) = f'(y)). Give an expression for Ly(a) in terms of y, f(y), and f'(y)