Use the Newton backward-difference formula to construct interpolating polynomials of degree one, two, and three for the following data. Approximate the specified value using each of the polynomials.
a. f (0.43) if f (0) = 1, f (0.25) = 1.64872, f (0.5) = 2.71828, f (0.75) = 4.48169
b. f (0.25) if f (−1) = 0.86199480, f (−0.5) = 0.95802009, f (0) = 1.0986123, f (0.5) = 1.2943767