Derive the formulas for the mean and the variance of the Poisson distribution by first evaluating E(X)

Question:

Derive the formulas for the mean and the variance of the Poisson by first evaluating E(X) and E[ X(X – 1)].
Distribution
The word "distribution" has several meanings in the financial world, most of them pertaining to the payment of assets from a fund, account, or individual security to an investor or beneficiary. Retirement account distributions are among the most...