Plzzz help Plz show how you got the answer

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).

Is there an x intercept in the equation 60*1.15^x

How many and of which kind of roots does the equation f(x)=2x^4−9x^3+17x^2−16x+6 have?