Can someone help me with this problem? :(

Determine the mean and variance of the random variable with the following probability mass function. f(x)=( 729divided by 91) (1 divided by 9) superscript x baseline comma x equals 1,2,3 round your answers to three decimal places (e. g. 98.765).

Triangle xyz has vertices x(1,3), y(0,0)

Show your workcan a right triangle have this sides? *how to prove it without using the pythagorean theorema*