# further pure 1Watch

#1
http://mathsathawthorn.pbworks.com/f/FP1Jun06.pdf
Could someone teach me how to start on q4?
The last time I did geometric series was in core 2 but ive forgot them:/
Is it a,ar, ar^2?
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1 year ago
#2
Form of a geometric series:

a + ar + ar^2

We know that the common ratio, r, is 2, so:

a + 2a + 4a.

This means that the first root is equal a, the second, 2a, and the third, 4a.
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1 year ago
#3
(Original post by English-help)
http://mathsathawthorn.pbworks.com/f/FP1Jun06.pdf
Could someone teach me how to start on q4?
The last time I did geometric series was in core 2 but ive forgot them:/
Is it a,ar, ar^2?
Yes the roots would be such that in order for them to be positive.

Then just equate from your knowledge of roots of cubic polynomials, and solve for .
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#4
(Original post by RDKGames)
Yes the roots would be such that in order for them to be positive.

Then just equate from your knowledge of roots of cubic polynomials, and solve for .
Okayy good
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