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There is an arithmetic sequence An where n is a positive integer such

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There is an arithmetic sequence An where n is a positive integer such  [#permalink]

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New post 08 Nov 2016, 02:15
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There is an arithmetic sequence An where n is a positive integer such that \(A_{n+1}=A_n+3\), what is the value of A10?

1) A1=3.
2) A3+A6=27

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Re: There is an arithmetic sequence An where n is a positive integer such  [#permalink]

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New post 10 Nov 2016, 01:17
==>In the original condition, there are 2 variables (An+1, An), and 1 equation (An+1=An+3), so D is highly likely to be the answer. 1)=2), so you get A10=30, hence unique, and sufficient. The answer is D.

Answer: D
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Re: There is an arithmetic sequence An where n is a positive integer such  [#permalink]

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New post 10 Nov 2016, 03:11
An+1=An+3. Difference between terms is 3.
nth term an arithmetic sequence, \(An = A1 + (n-1)*D\)
An = A1 + (n-1)*3
\(A10 = A1 + 9 *3\)
To find A10, it is sufficient to find A1

1) A1=3.

A1 is known, hence sufficient.

2) A3+A6=27
A1+ (2-1)*3 + A1 + (6-1)*3 = 27
2A1 = 9
A1 = 4.5
Hence sufficient.

Each statement alone is sufficient. Option D
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Re: There is an arithmetic sequence An where n is a positive integer such  [#permalink]

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New post 13 Nov 2016, 22:49
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Please use mathematical indentation. The question becomes unclear otherwise.
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Re: There is an arithmetic sequence An where n is a positive integer such  [#permalink]

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New post 07 Jan 2017, 23:41
great post - do you mind elaborating on how you got the difference between terms being 3?

rudra316 wrote:
An+1=An+3. Difference between terms is 3.
nth term an arithmetic sequence, \(An = A1 + (n-1)*D\)
An = A1 + (n-1)*3
\(A10 = A1 + 9 *3\)
To find A10, it is sufficient to find A1

1) A1=3.

A1 is known, hence sufficient.

2) A3+A6=27
A1+ (2-1)*3 + A1 + (6-1)*3 = 27
2A1 = 9
A1 = 4.5
Hence sufficient.

Each statement alone is sufficient. Option D
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Re: There is an arithmetic sequence An where n is a positive integer such  [#permalink]

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New post 08 Jan 2017, 00:00
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mdacosta wrote:
great post - do you mind elaborating on how you got the difference between terms being 3?

rudra316 wrote:
An+1=An+3. Difference between terms is 3.
nth term an arithmetic sequence, \(An = A1 + (n-1)*D\)
An = A1 + (n-1)*3
[



Hi,

The Q is complicated because the author has not used mathematical notations and has left each one to think their own way..
\(A_{n+1}=A_n+3\)...
So (n+1) th term is 3 more than the nth term.

We have to find \(A_10\)...
From the equation \(A_{n+1}=A_n+3\), we know that each term is related to every other term
Thus web just require to know any term.

Both statements give us a value and a variable, so both will give us a answer..
Suff

D
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Re: There is an arithmetic sequence An where n is a positive integer such  [#permalink]

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New post 08 Jan 2017, 00:16
Thanks chetan !! Those notations ate my time..
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Re: There is an arithmetic sequence An where n is a positive integer such  [#permalink]

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New post 20 Feb 2018, 11:18
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MathRevolution wrote:
There is an arithmetic sequence An where n is a positive integer such that An+1=An+3, what is the value of A10?

1) A1=3.
2) A3+A6=27


Very Poor way of writing the question, Moderator should edit the question so that it appears in the correct format.
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Re: There is an arithmetic sequence An where n is a positive integer such   [#permalink] 20 Feb 2018, 11:18
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