# Week 1 – precalculus 11

This week in Pre calculus11, I learned about the Arithmetic sequence. This lesson was an easy lesson, but I had a little bit of struggling at first when I had to solve the question that seemed a little bit hard for me, but after several practicing, I learned how to solve the question, Here is the Example:

Example 1: How many terms are in the sequence 2, 6, 10, 14,…….,50

first step:

we know the first term is 2, the common difference is 4, and we say the $t_n$ is 50

second step:

the equation is=> $t_n$$t_1$ +(n-1)d

third step:

Now we could put  the things that we know in the equation:

50= 2 +(n-1)4

forth step:

we don’t know what is n in (n-1) so we would multiply the common difference which is 4 by n and -1

50= 2 +4n-4

Last step:

so now we put the unknown on one side and the known on the other side

50-2+4= 4n

52= 4n

$\frac{52}{4}$=$\frac{4}{4}$

n= 13

so there are 13 terms in that sequence