Problem 6.7, how to combine the function given and the Tchebychev inequality?

6.7 Define the subsets of the real line Fn = [r: | r| > ) ,n = 1,2,... n and F = 10) . Show that FC = UF . Use this fact, the Tchebychev inequality, and the continuity of proba- bility to show that if a random variable X has variance 0, then Pr( X - EX| 2) 50 independent of e and hence Pr(X = EX) = 1