maths remainder thm.

Let f(x)=x^3 +ax^2 +bx -1. When f(x) is divided by x+1 and x-2, the remainders are -13 and 11 respectively.
(a)find the values of a and b
(b)find f(x+1)
(c)find the remailder of f(x+1) / (x+2)