Let X∼Exponential(λ)X \sim \text{Exponential}(\lambda)X∼Exponential(λ). What is E[X2]E[X^2]E[X2]?
1/λ21/\lambda^21/λ2
2/λ22/\lambda^22/λ2
1/λ1/\lambda1/λ
2/λ2/\lambda2/λ