Consider these methods:

public static double f(double x) { return g(x) + Math.sqrt(h(x)); }
public static double g(double x) { return 4 * h(x); }
public static double h(double x) { return x * x + k(x) - 1; }
public static double k(double x) { return 2 * (x + 1); }
Without actually compiling and running a program, determine the results of the
following method calls.
a. double x1 = f(2);
b. double x2 = g(h(2));
c. double x3 = k(g(2) + h(2));
d. double x4 = f(0) + f(1) + f(2);
e. double x5 = f(-1) + g(-1) + h(-1) + k(-1);