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The terms of the sequence {An} satisfy A2 - A1 = 2, A3 - A2 = 5 and A4

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Re: The terms of the sequence {An} satisfy A2 - A1 = 2, A3 - A2 = 5 and A4 [#permalink]
=>

We try each possibility until we find a formula that works.
A): If An+1 - An = n + 1, then A2 - A1 = $$1 + 1 = 2$$, which is correct, but
A3 - A2 = $$2 + 1 = 3 ≠ 5.$$
So, A) is not the answer.
B): If An+1 - An = $$n^2 +$$1, then
A2 - A1 = $$1^2 + 1 = 2,$$
A3 - A2 =$$2^2 + 1 = 5,$$
A4 - A3 = $$3^2 + 1 = 10.$$
So, this formula is possible.

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Re: The terms of the sequence {An} satisfy A2 - A1 = 2, A3 - A2 = 5 and A4 [#permalink]
A2-A1=2, A3-A2=5
putting n=2 difference is 5
A.n+1
2+1=3 incorrect
B.n^2+1
C.n^2−1
2^2-1=3
Incorrect
D.n−1
2-1=1 incorrect
E.n^2+3
2^2+3=7 incorrect

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Re: The terms of the sequence {An} satisfy A2 - A1 = 2, A3 - A2 = 5 and A4 [#permalink]
MathRevolution wrote:
=>

We try each possibility until we find a formula that works.
A): If An+1 - An = n + 1, then A2 - A1 = $$1 + 1 = 2$$, which is correct, but
A3 - A2 = $$2 + 1 = 3 ≠ 5.$$
So, A) is not the answer.
B): If An+1 - An = $$n^2 +$$1, then
A2 - A1 = $$1^2 + 1 = 2,$$
A3 - A2 =$$2^2 + 1 = 5,$$
A4 - A3 = $$3^2 + 1 = 10.$$
So, this formula is possible.

Hi Math Revolution good question could you list some similar questions ?

Bunuel if you would know some similar sums will really help!
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Re: The terms of the sequence {An} satisfy A2 - A1 = 2, A3 - A2 = 5 and A4 [#permalink]
Sri07 wrote:
MathRevolution wrote:
=>

We try each possibility until we find a formula that works.
A): If An+1 - An = n + 1, then A2 - A1 = $$1 + 1 = 2$$, which is correct, but
A3 - A2 = $$2 + 1 = 3 ≠ 5.$$
So, A) is not the answer.
B): If An+1 - An = $$n^2 +$$1, then
A2 - A1 = $$1^2 + 1 = 2,$$
A3 - A2 =$$2^2 + 1 = 5,$$
A4 - A3 = $$3^2 + 1 = 10.$$
So, this formula is possible.

Hi Math Revolution good question could you list some similar questions ?

Bunuel if you would know some similar sums will really help!

12. Sequences

For other subjects:
ALL YOU NEED FOR QUANT ! ! !

Hope it helps.
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Re: The terms of the sequence {An} satisfy A2 - A1 = 2, A3 - A2 = 5 and A4 [#permalink]
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Re: The terms of the sequence {An} satisfy A2 - A1 = 2, A3 - A2 = 5 and A4 [#permalink]
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