50. Show that if f(x) = a,x" + a-1x+...+x+ ao, a,..., a-1, and a,, are real numbers and where 0, then f(x) is O(x"). an # Big-O, big-Theta, and big-Omega notation can be extended to functions in more than one variable. For example, the state- ment f(x, y) is O(g(x, y)) means that there exist constants C, k, and k such that f(x, y)| Clg(x, y)| whenever x > k and y > k.