7.4 A recursive function is a function defined by a finite set of rules that for various arguments specify the function in terms of variables, nonnegative integer constants, the successor (add one) function, the function itself, or an expression built from these by composition of functions. For example, Ackermann's function is defined by the rules: 1) A(0, y)-I 2) A(1, 0)-2 3) A(x, 0)-x + 2 for x 22 a) Evaluate A(2, 1) * b) what function of one variable is A(x, 2)? * c) Evaluate A(4, 3)