Write the formula for the general term of the sequence. Assume the first term of the sequence corresponds to n = 1.
9, 18, 27, 36,...
The first thing we'll do for the sequence is make a table to help us see the relationship between n and an.
If you look at this as similar to the previous sequence, each term is some amount less than a multiple of 10. Which multiple of 10, and the amount less, both depend on n.
The general term is
an = 10n – n.
If you look at this sequence from scratch, you're more likely to see
Now the general term is an = 9n.