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# Geometric sequence question watch

1. Hi , stuck on the below question.

If 3, x and 9 are the first three terms of a geometric sequence. Find the exact value of x.

Thought it might be

(u_2) / (u_1) = (u_3) / (u_2) as using the two rules to get the common ratio.

But I get SQRT(27) so not sure if that is right
Hi , stuck on the below question.

If 3, x and 9 are the first three terms of a geometric sequence. Find the exact value of x.

Thought it might be

(u_2) / (u_1) = (u_3) / (u_2) as using the two rules to get the common ratio.

But I get SQRT(27) so not sure if that is right
That should be correct
Hi , stuck on the below question.

If 3, x and 9 are the first three terms of a geometric sequence. Find the exact value of x.

Thought it might be

(u_2) / (u_1) = (u_3) / (u_2) as using the two rules to get the common ratio.

But I get SQRT(27) so not sure if that is right
That's correct so far - don't forget it can be plus or minus.

By "exact value" they mean leave it in surd form.
4. (Original post by SeanFM)
That should be correct
(Original post by ghostwalker)
That's correct so far - don't forget it can be plus or minus.

By "exact value" they mean leave it in surd form.
Ah thank you both.

Just used it to see if it works in the sequence (which I should of done first) and it works

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Updated: November 8, 2015
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