How do i show work for the circled question?

Is a positive integer raised to a negative power always positive

An optical inspection system is used to distinguish among different part types. the probability of a correct classification of any part is 0.92. suppose that three parts are inspected and that the classifications are independent. let the random variable x denote the number of parts that are correctly classified. determine the probability mass function of x. round your answers to four decimal places (e. g. 98.7654). x f(x) 0 1 2 3

Find the common ratio of the sequence. -4, 8, -16, 32, a: -12b: -2c: 12d: -1/-2