# Week 16 – Math 10

This week we started our unit on Sequences. Sequences are how terms change consecutively, whether they go up and down by the same amount (Arithmetic). Multiplying or dividing (Geometric). Or another way (Other Sequences).

This will focus on arithmetic sequences, sequences that go up or down by the same amount.

In a sequence where you are only given one number, you will likely be given $d$, which stands for difference as in the difference between the two numbers. If it is positive, then it goes up as you move to the left and down as you go to the right, and if it’s negative, it’s vice versa.

ex.

_,_,_,0,_,_ $d=2$ to  -6, -4, -2, 0, 2, 4

If you are looking for a specific term or number in an arithmetic sequence, you can find it rather easily without having to use the rule over and over again until you get to that term.

If you use a specific formula, you can find the number you need without finding the difference over and over again.

Here is the formula and what it all means: 