What does tan^2(x) mean

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).

Write the function for the graph. (1.8) (0,4)

What number is 7 units left of -15?