Solve both questions a & b

Consider the following model for the random sample x = ($1, T2, . ..,, ), where Di >0 for i = 1, 2, . .., n: f(ra, b) = abe-abr a, b >0. To represent your beliefs on the unknown parameters a and b, you use the following joint density: n(a, b) = e- a, b >0. (a) Find the likelihood function for the above sample x. (b) Derive the joint posterior distribution, #(a, box), for the vector of parameters (a, b) T