# What is the algebraic expression for sum of the sequence #7,11,15#?

##### 2 Answers

#### Explanation:

The sum of the sequence means adding;

This means the sequence turns to

We want to find the N'th term, we do this by finding the difference in the sequence:

Finding the difference of the differences:

To find the quadratic of the N'th term, we divide this by

Now we take away

We only need the first

Finding the difference between the differences:

Therefore we

This gives us:

We can check this by substituting the values of

Alternate...

#### Explanation:

The sequence is defined by:

Hence we are trying to find the sum of the first

In sigma notation

We can use our knowledge of series...

We also know..