# The first three terms of an arithmetic sequence are given by x, (2x-5), 8.6 ?

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a) determine the first term and the common difference for the sequence

b) determine the 20th term of the sequence

c) determine the sum of the first 20 terms of the series

a) determine the first term and the common difference for the sequence

b) determine the 20th term of the sequence

c) determine the sum of the first 20 terms of the series

##### 1 Answer

A: First term is

B:

C:

#### Explanation:

Question A:

Since this is an arithmetic sequence, there are two sides of the equation:

Simplify.

Hence, the first term is

This means that the common difference is

Question B:

Let's consider terms as

Let's consider the answers as

Therefore, the 20th term would be:

Question C:

The easiest way to find a sum would be with this formula.

There are 20 terms in the sequence.

Substituting, you would get this:

Solve.