[schoolrun]

Ok very simple, please look at the picture attached. I just dont get the beginning of part iv. Why is the relevant value (3-root5)/2 and not (3+root5)/2?

[z95]

The question states that the progression is convergent. Therefore, the common ratio for the sequence is a decimal. As only (3-root5)/2 fits the category, you need to use that solution

[schoolrun]

(Original post by z95)
The question states that the progression is convergent. Therefore, the common ratio for the sequence is a decimal. As only (3-root5)/2 fits the category, you need to use that solution

Thanks for your reply,
(3+root5)/2 is also a decimal though

(I have repped you for your answer)

[z95]

(Original post by schoolrun)
Thanks for your reply,
(3+root5)/2 is also a decimal though

(I have repped you for your answer)

Sorry what I meant was that r is between -1 and 1. Sorry for not being clear an thanks for the rep