For example lets say the numbers given are 1, 5, 9, ... To find the common difference, you subtract the 1st term from the 2nd term. In this case, we would do 5 - 1, which equals 4.
We must add the common difference to the last term in order to find the next term. Since the common difference is 4, we add 4 to 9, which makes 13. This applies only in the arithmetic sequence.
True, because if there is an example: 3, 6, 9, 12... The common difference is 3. If you want to find out what comes after 12 you need to add 3, so 12+3= 15, so the next term is 15!
