SOLUTION: x,2x+1,11 are three consecutive terms of an arithmetic sequence. Calculate(i) x.(ii) the 30th term.

Question 1127070: x,2x+1,11 are three consecutive terms of an arithmetic sequence. Calculate(i) x.(ii) the 30th term.
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x,2x+1,11 are three consecutive terms of an arithmetic sequence. Calculate(i) x.(ii) the 30th term.
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x,2x+1,11 are the first three terms of an arithmetic sequence. Calculate(i) x.(ii) the 30th term.
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x + d = 2x + 1 �> d = x + 1 (1)
(2x + 1) + d = 11 �> d = 10 - 2x (2)

Set (1) equal to (2): x + 1 = 10 - 2x
3x = 9
x = 3

d = x + 1 �> d = 4

(i)

(ii) To find an answer, it must be assumed that the three terms given are the FIRST three terms (or at least their position m must be given) of the sequence (the problem statement does not provide sufficient information).

...

Plugging in n=30:

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