In Problems 1 through 12, in each case determine whether or not the function f is continuous at the given value of a. If it is not continuous, decide whether or not the function is continuous on the left or on the right. State reasons for each step in the argument as in the Example. 1. f(x) = x - 4, (x² - 6, -1<x<2, a = 2 2<x<5,