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# maths watch

1. 6 An arithmetic progression has first term 7 and third term 12. (i) Find the 20th term of this progression.
(ii) Find the sum of the 21st to the 50th terms inclusive of this progression.
2. (Original post by aimen:P)
6 An arithmetic progression has first term 7 and third term 12. (i) Find the 20th term of this progression.
(ii) Find the sum of the 21st to the 50th terms inclusive of this progression.
Let's call the second term x

therefore:

To find a common difference we just find the difference in consecutive terms right?
So,

So now you can find the common difference
3. thank you! i think i get it now
(Original post by LelouchViRuge)
Let's call the second term x

therefore:

To find a common difference we just find the difference in consecutive terms right?
So,

So now you can find the common difference

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