Math CentralQuandaries & Queries


Question from collins, a student:

In an A.P. the difference between the 8th and 4th term is 20 and the 8th is one and half times the 4th term...what is the common difference and the first term

Hi Collins,

I can help get you started.

In an Arithmetic Progression, AP, the difference or step between any two consecutive terms is the same. This step is called the common difference. For example in the AP 6, 9, 12, 15, ... each term is 3 more than the previous term so the common difference is 3.

In your AP the difference between the 4th and 8th terms is 20. How many steps are there from the 4th term to the 8th term? How large is each step?


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