Sum of an Arithmetic Series help required! (1 Viewer)

[Carl5]

This is the first time I've done a question like this and my book doesn't have an example.

The sum of the first 5 terms of an arithmetic series is 110 and the sum of the first 10 terms is 320. Find the first term and the common difference.

 

[Amogh]

Make two equations using the sum of an A.P series equation, and then solve simultaneously.
Remember:

is the Sum till the nth term, for an Arithmetic progression starting with 'a', with a common difference of 'd'.

 

[Ishynooshy]

You need to use the formula to find the sum of an arithmetic series with n terms. Substitute n and the final value of the sum into the formula for the two conditions. This will form two simultaneous equations that you can then solve for a, the first term, and d, the common difference.

 

[Carl5]

Ahh, I feel silly now haha

Thank you, worked it out easy !