Hey if anyone could help me with this I would be sooo grateful. Im trying to grasp the idea of onto, one-to-one and bijection(both) functions. A sample problem is: If f(x) = 2x . What is f(Z), all integers. What is f(N), all naturals. What is f(R), all real. These are 3 different problems, and im trying to figure out if they are onto, and/or one-to-one or bijection(which means both). Any help would be a BIG HELP! Thanks!