# Aqa C2 Sequences

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Hey

I've got a C2 resit on Friday and have been doing some past papers

I understand pretty much all of it but can't get my head around a certain part of the sequences chapter.

An example of a question (January 06) that i don't have a clue about is:

The nth term of a sequence is Un

The sequence is defined by U(n+1) = pUn + q

The first three terms of the sequence are given by

U1= 200 U2= 150 U3= 120

a) Show that p= 0.6 and find the value of p

I understand this and came out with p=0.6 and q= 30

b) Find the value of U4

I also understand this and came out with U4 = 102

c) The limit of Un as n tends to infinity is L. Write an equations for L and hence find the value of L

I have absolutely no clue where to start with the question, any help would be much appreciated thanks

I've got a C2 resit on Friday and have been doing some past papers

I understand pretty much all of it but can't get my head around a certain part of the sequences chapter.

An example of a question (January 06) that i don't have a clue about is:

The nth term of a sequence is Un

The sequence is defined by U(n+1) = pUn + q

The first three terms of the sequence are given by

U1= 200 U2= 150 U3= 120

a) Show that p= 0.6 and find the value of p

I understand this and came out with p=0.6 and q= 30

b) Find the value of U4

I also understand this and came out with U4 = 102

c) The limit of Un as n tends to infinity is L. Write an equations for L and hence find the value of L

I have absolutely no clue where to start with the question, any help would be much appreciated thanks

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#2

(Original post by

Hey

don't have a clue about is:

The nth term of a sequence is Un

The sequence is defined by U(n+1) = pUn + q

c) The limit of Un as n tends to infinity is L. Write an equations for L and hence find the value of L

I have absolutely no clue where to start with the question, any help would be much appreciated thanks

**Limlove**)Hey

don't have a clue about is:

The nth term of a sequence is Un

The sequence is defined by U(n+1) = pUn + q

c) The limit of Un as n tends to infinity is L. Write an equations for L and hence find the value of L

I have absolutely no clue where to start with the question, any help would be much appreciated thanks

OK you have:

And you need to take the limit as n tends to infinity. So:

And:

Thus:

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Thanks for the help ghostwalker!

I've just had a look at the mark scheme and it goes even further than that

it states the equation 'L = 0.6L +30' for one mark

but then for the the other two marks it says :

L = q / (1-p)

L = 75

I'm guessing this has something to do with the equation a/(1-r) but im not really sure where to go form there?

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#5

(Original post by

Thanks for the help ghostwalker!

I've just had a look at the mark scheme and it goes even further than that

it states the equation 'L = 0.6L +30' for one mark

but then for the the other two marks it says :

L = q / (1-p)

L = 75

I'm guessing this has something to do with the equation a/(1-r) but im not really sure where to go form there?

**Limlove**)Thanks for the help ghostwalker!

I've just had a look at the mark scheme and it goes even further than that

it states the equation 'L = 0.6L +30' for one mark

but then for the the other two marks it says :

L = q / (1-p)

L = 75

I'm guessing this has something to do with the equation a/(1-r) but im not really sure where to go form there?

You may find it easier to do that this way though:

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#6

**Limlove**)

Thanks for the help ghostwalker!

I've just had a look at the mark scheme and it goes even further than that

it states the equation 'L = 0.6L +30' for one mark

but then for the the other two marks it says :

L = q / (1-p)

L = 75

I'm guessing this has something to do with the equation a/(1-r) but im not really sure where to go form there?

Then you need to solve the equation, to find L.

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TSR saves me again!!

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#8

(Original post by

Hey

I've got a C2 resit on Friday and have been doing some past papers

I understand pretty much all of it but can't get my head around a certain part of the sequences chapter.

An example of a question (January 06) that i don't have a clue about is:

The nth term of a sequence is Un

The sequence is defined by U(n+1) = pUn + q

The first three terms of the sequence are given by

U1= 200 U2= 150 U3= 120

a) Show that p= 0.6 and find the value of p

I understand this and came out with p=0.6 and q= 30

b) Find the value of U4

I also understand this and came out with U4 = 102

c) The limit of Un as n tends to infinity is L. Write an equations for L and hence find the value of L

I have absolutely no clue where to start with the question, any help would be much appreciated thanks

**Limlove**)Hey

I've got a C2 resit on Friday and have been doing some past papers

I understand pretty much all of it but can't get my head around a certain part of the sequences chapter.

An example of a question (January 06) that i don't have a clue about is:

The nth term of a sequence is Un

The sequence is defined by U(n+1) = pUn + q

The first three terms of the sequence are given by

U1= 200 U2= 150 U3= 120

a) Show that p= 0.6 and find the value of p

I understand this and came out with p=0.6 and q= 30

b) Find the value of U4

I also understand this and came out with U4 = 102

c) The limit of Un as n tends to infinity is L. Write an equations for L and hence find the value of L

I have absolutely no clue where to start with the question, any help would be much appreciated thanks

Just sat this paper for revision

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#9

(Original post by

Hi, how did you get U4 for part b?

Just sat this paper for revision

**M.Johnson2111**)Hi, how did you get U4 for part b?

Just sat this paper for revision

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#10

(Original post by

By now Limlove has probably forgotten that TSR exists.

**Plücker**)By now Limlove has probably forgotten that TSR exists.

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#11

(Original post by

Probably but hopefully not, the mark sheme doesnt provide much help and I can't find other online solutions

**M.Johnson2111**)Probably but hopefully not, the mark sheme doesnt provide much help and I can't find other online solutions

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#12

Thank you, your format makes a lot more sense where it says U3 I was writing U5 so must of wrote n+1 anyhow thank you

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