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# The infinite sequence a1,a2,a3,…an can be expressed as an=an−1+4 for

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Math Expert
Joined: 02 Sep 2009
Posts: 50039
The infinite sequence a1,a2,a3,…an can be expressed as an=an−1+4 for  [#permalink]

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17 Apr 2018, 05:11
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Difficulty:

15% (low)

Question Stats:

94% (01:26) correct 6% (02:01) wrong based on 43 sessions

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The infinite sequence $$a_1$$, $$a_2$$, $$a_3$$, … $$a_n$$ can be expressed as $$a_n=a_{n−1}+4$$ for all n > 1 and $$a_1=3$$. which of the following equations could also represent an for all n > 1?

A. $$a_n = 4n+1$$

B. $$a_n=4n–1$$

C. $$a_n=n+4$$

D. $$a_n=4n–7$$

E. $$a_n=3n+4$$

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Re: The infinite sequence a1,a2,a3,…an can be expressed as an=an−1+4 for  [#permalink]

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17 Apr 2018, 06:28
Bunuel wrote:
The infinite sequence $$a_1$$, $$a_2$$, $$a_3$$, … $$a_n$$ can be expressed as $$a_n=a_{n−1}+4$$ for all n > 1 and $$a_1=3$$. which of the following equations could also represent an for all n > 1?

A. $$a_n = 4n+1$$

B. $$a_n=4n–1$$

C. $$a_n=n+4$$

D. $$a_n=4n–7$$

E. $$a_n=3n+4$$

The sequence given is an Arithmetic Progression with a difference of $$4$$ $$(d=4)$$.
For Arithmetic Progression $$a_n = a_1 + d(n - 1)$$ equation holds true.

So, $$a_n = 3 + 4(n - 1) = 4n - 1$$

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Tulkin.

Re: The infinite sequence a1,a2,a3,…an can be expressed as an=an−1+4 for &nbs [#permalink] 17 Apr 2018, 06:28
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