How do you transform roster method to ruler method and vice versa?

Answer 1

You probably are thinking of the "rule" method for specifying a function.

In roster form, a function might look like this: {(1,3), (2,5), (3,7), (4,9), ...}. To change to the rule form, you need to see the pattern in the function and write it as an algebraic expression. The second numbers in the pairs are the odd numbers starting with 3, but this doesn't really help to write a rule. You need to say that "to find the second number, we double the first number and add 1."

This gives the rule {x, (2x+1)} or y= 2x+1.

If you are given a rule, you can find the roster simply by picking numbers for x and finding the corresponding values of y. Make up the roster by putting the x-values first and the y-values second in each ordered pair.