## Wednesday, September 16, 2015

### High School Math Solutions – Sequence Calculator, Sequence Examples

In the last post, we talked about sequences. In this post, we will focus on examples of different sequence problems. We will not go through them step by step, but the examples will give you a better feel for how to solve these problems.

Here is a simple example of when we use substitution to find a term (click here):

In this last example, we find the sum of the 4th term to the 100th term (click here):

Try out some of the examples of sequences we have on our site. The more you practice the better you will get!

Until next time,

Leah

## Tuesday, September 8, 2015

### High School Math Solutions – Algebra Calculator, Sequences

When dealing with simpler sequences, we can look at the sequence and get a feel for what the next term or the rule is.  However, not all sequences are nice like those. Finding the rule of a sequence can be difficult if you don’t know where to begin. We will focus on arithmetic and geometric sequences, which will make finding the rule, term, and sum of terms very easy.

Arithmetic Sequence:
• A sequence where the difference between the consecutive terms is constant
• Finding the nth term: a_n=a_1+(n-1)d
• Find the sum of n terms: S_n=\frac{n(a_1+a_n)}{2}

Geometric Sequence:
• A sequence where each term is multiplied the previous term by a constant
• Finding the nth term: a_n=a_0\cdot r^{n-1}
• Find the sum of n terms: S_n=\frac{a_1(1-r^n)}{1-r}

Here we will go through a problem involving an arithmetic sequence step by step (click here):

1. See if you can see a pattern
Find the next 3 terms of the following sequence: 3,11,19,27,35,...
We can see that difference in each term is 8.
2. Plug terms into the formula
a_n=a_1+(n-1)d
a_n=3+(n-1)8
3. Compute terms
a_6=3+(6-1)8=43
a_7=3+(7-1)8=51
a_8=3+(8-1)8=59

We will now go through a problem involving a geometric sequence step by step (click here):
Find the 7th term of the following sequence:  \frac{2}{9},\frac{2}{7},2,6,18
1. Check to see if the ratio is constant

2. Plug terms into formula
a_n=a_0∙r^(n-1)
a_n=\frac{2}{9}\cdot 3^(n-1)
3. Compute term
a_7=\frac{2}{9}\cdot 3^6=162

Here’s an example where you have to find the sum of terms (click here):

Arithmetic and geometric series aren’t very hard. Just memorize the formulas and it should be pretty easy.

Until next time,
Leah