4. If we draw some dots on a paper, and connect each one of them to every other one with a single line, how many lines will we draw? Using mathematical induction, prove that the number of lines for n dots is 1/n (n 1). Here is an example of the first few cases: 3 dots, 3 lines 4 dots, 6 lines 5 dots, 10 lines 6 dots, 15 lines 7 dots, 21 lines