Let x1 xn be iid random variables from pa where a r2 is

Question

Let X₁, ..., X_n be i.i.d. random variables from P_(a,θ), where (a, θ) ∈ R² is a parameter. Find a two-dimensional sufficient statistic for (a, θ) in the following cases.

(a) P(a,θ) is the exponential distribution E(a, θ), a ∈ R, θ ∈ (0, ∞).

(b) P(a,θ) is the Pareto distribution Pa(a, θ), a ∈ (0, ∞), θ ∈ (0, ∞).