Help with Maths question Watch

Lala143
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Find an expression for the sum of the (n-1)th and nth terms of this sequence. Give answers in simplest form.
I have worked it out but I don't understand my working out anymore.
My working out: 4n+1+4(n-1)+1
=8n-2
I don't know where I got: 4n+1+4(n-1)+1
Can someone explain how this is correct because it was marked correct?
I'm not saying it is incorrect I just don't know how I worked it out.
The previous question was the nth term of an arithmetic sequence is 4n+1 where n is a positive integer.
Is 95 a term in this sequence?
My answer(which was correct): 95=4n+1
23.5=n
n isn't a term in this sequence.
Last edited by Lala143; 1 week ago
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Lala143
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bump
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Lala143
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BuMp
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Lala143
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bumP
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Muttley79
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(Original post by Lala143)
bumP
Stop bumping the thread - where is the sequence?
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Lala143
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There is no sequence but the equation for the sequence is 4n+1
(Original post by Muttley79)
Stop bumping the thread - where is the sequence?
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Muttley79
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(Original post by Lala143)
There is no sequence but the equation for the sequence is 4n+1
So you were told the nth term of the sequence was 4n + 1?
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ethancruise15
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There will be a sequence or this question makes no sense
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haseebj49
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(Original post by Lala143)
Find an expression for the sum of the (n-1)th and nth terms of this sequence. Give answers in simplest form.
I have worked it out but I don't understand my working out anymore.
My working out: 4n+1+4(n-1)+1
=8n-2
I don't know where I got: 4n+1+4(n-1)+1
Can someone explain how this is correct because it was marked correct?
I'm not saying it is incorrect I just don't know how I worked it out.
The previous question was the nth term of an arithmetic sequence is 4n+1 where n is a positive integer.
Is 95 a term in this sequence?
My answer(which was correct): 95=4n+1
23.5=n
n isn't a term in this sequence.
The question is asking for the sum of 2 consecutive numbers of the sequence...
Imagine you are trying to calculate the values when n=2 and n=1.
n=1 is one less than n=2 so therefore it is n-1. So mathematically you are using the 'n' th and the 'n-1' th term
You substitute that into the original 4n+1 to get 4n+1 + 4(n-1) +1 to calculate the sum of the nth and n-1th term and you get your answer (:
Hope this helps!
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Lala143
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(Original post by ethancruise15)
There will be a sequence or this question makes no sense
ok
Last edited by Lala143; 1 week ago
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Lala143
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How did you get from n=1 is one less than n=2 so, therefore, it is n-1. So mathematically you are using the 'n' th and the 'n-1' th term to 4n+1 + 4(n-1) +1?
(Original post by haseebj49)
The question is asking for the sum of 2 consecutive numbers of the sequence...
Imagine you are trying to calculate the values when n=2 and n=1.
n=1 is one less than n=2 so therefore it is n-1. So mathematically you are using the 'n' th and the 'n-1' th term
You substitute that into the original 4n+1 to get 4n+1 + 4(n-1) +1 to calculate the sum of the nth and n-1th term and you get your answer (:
Hope this helps!
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haseebj49
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(Original post by Lala143)
How did you get from n=1 is one less than n=2 so, therefore, it is n-1. So mathematically you are using the 'n' th and the 'n-1' th term to 4n+1 + 4(n-1) +1?
The question states that you want the sum of the (n-1)th term and the nth term.
I just gave you the n=2 and n=1 as an example to show 2 consecutive numbers which is what the question is asking for
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Muttley79
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(Original post by haseebj49)
The question is asking for the sum of 2 consecutive numbers of the sequence...
Imagine you are trying to calculate the values when n=2 and n=1.
Please follow forum guidelines in future and just give a hint - we do not allow solutions
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Muttley79
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(Original post by Lala143)
How did you get from n=1 is one less than n=2 so, therefore, it is n-1. So mathematically you are using the 'n' th and the 'n-1' th term to 4n+1 + 4(n-1) +1?
Did you read my reply? If the nth term is 4n + 1 then to get the (n-1)th term we substitute (n-1) into the rule instead of n.
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haseebj49
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(Original post by Muttley79)
Please follow forum guidelines in future and just give a hint - we do not allow solutions
Thought it would be okay since OP got the answer but was confused about the workings...
But I'll bear that in mind next time (:
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Lala143
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Thanks for helping me make sense of this.
(Original post by haseebj49)
The question states that you want the sum of the (n-1)th term and the nth term.
I just gave you the n=2 and n=1 as an example to show 2 consecutive numbers which is what the question is asking for
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