Got class in 30 mins, 3 problems I dont know how to solve

These are incredibly difficult

2) A fourth degree polynomial f(x) with real coefficients and leading coefficient of 1 has zeroes of -1, 2,1 -i. Write the polynomial as a product of linear and quadratic factors with real coefficients that are irreducible over R (this R represents the real number like I think)

2) Find values a,b, and c for exponential function f(x) = cb^-x + a. Given that the horizontal asymptote is y = 72. Y intercept is 425 and point P (1,248.5) lies on the graph.

I did y=mx + b and got M=176.5 but what about the rest (c,b,a,x)?

3) Determine the domain and range of f^1 for the function f(x) = (4x+5)/(3x-8), without actually finding f^1