Which of the following class definitions defines a legal abstract class?

abstract class a { abstract void unfinished(); }

public class abstract a { abstract void unfinished(); }

class a { abstract void unfinished(); }

class a { abstract void unfinished() { } }

The following function returns a string of length n whose characters are all 'x'. give the order of growth (as a function of n) of the running time. recall that concatenating two strings in java takes time proportional to the sum of their lengths. public static string f(int n) { if (n == 0) return ""; if (n == 1) return "x"; return f(n/2) + f(n - n/2); } options: a) constant b) logarithmic c) linear d) linearithmic e)quadratic f)cubic g) exponential

Your computer running windows 10 is doing some very strange things with the operating system. you are fairly certain it is not a hardware issue. you need to try to get further insight into what is going on within the operating system. which tool would be best suited for this?

Whats three fourths of 15(this is supposed to be in math but i clicked too fast)