(2 points) Consider the production function f (1, (2) = (x2 + x,) where a > 0 and B>O. (a Find the marginal product of input 1 and input 2. (1 point) (b) For which values of the parameters a and S does this production function exhibit increasing returns to scale (IRS), constant returns to scale (CRS), and decreasing returns to scale (DRS)? (1 point)