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Reccurence relations

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Question 3

how do i know that U1U_1 =1?
Reply 1
Avatar for nerak99
nerak99
13
Original post by thefatone


You don't. You know that u1=2+ku_1=2+k
Reply 2
Avatar for thefatone
thefatone
OP
6
Original post by nerak99
You don't. You know that u1=2+ku_1=2+k


but you do to reach that conclusion

look you just put in n=1 to get out of the reccurence relation what you've stated but how do i know that

n=1???
Reply 3
Avatar for nerak99
nerak99
13
Well, for a start, I would not really call this a recurrence relation. It is a formula where we are told that
un=2n+knu_n=2^n+kn Hence, if n=1 u1=21+ku_1=2^1+k.

Otherwise, I do not understand your question. Yes, I just put in n=1 but that is what is required here.

It turns out that u1=−1u_1=-1 anyway.
(edited 7 years ago)
Reply 4
Avatar for thefatone
thefatone
OP
6
Original post by nerak99
Well, for a start, I would not really call this a recurrence relation. It is a formula where we are told that
un=2n+knu_n=2^n+kn Hence, if n=1 u1=21+ku_1=2^1+k.

Otherwise, I do not understand your question. Yes, I just put in n=1 but that is what is required here.


how do you know this where have you gotten n=1 from? why isn't n=2?
Reply 5
Avatar for nerak99
nerak99
13
We are told in a) that u1=u3u_1=u_3and we have used that fact.

I think you should go off and have a rest and come back later.

From your previous post have you not done C1 or was that agonising just about a practice paper?
Reply 6
Avatar for thefatone
thefatone
OP
6
Original post by nerak99
We are told in a) that u1=u3u_1=u_3and we have used that fact.

I think you should go off and have a rest and come back later.

From your previous post have you not done C1 or was that agonising just about a practice paper?

that was me being super annoyed about the fact that i can't not make stupid mistakes
yes i do need a rest but i can't afford one, i need to do more C1
Original post by Malandirix
The n is different for each term. In the case of u1 n=1
in the case of u3 n = 3


i see so the number below the u is the number n= ..... right thanks
Reply 7
Avatar for nerak99
nerak99
13
Well that is OK. I will take your future rep award as an apology.
Reply 8
Avatar for Zacken
Zacken
22
Original post by thefatone
...


The formula says that the given relation is true for all natural n. You can plug in whatever n you want, plug in n=2 if you want. It'll just be utterly useless and a waste of your time. The only useful ones you get is from n=1n=1 and n=3n=3. If you can't see why that is the most useful ones to plug in, then you really do need to have a rest.
Reply 9
Avatar for thefatone
thefatone
OP
6
Original post by Zacken
The formula says that the given relation is true for all natural n. You can plug in whatever n you want, plug in n=2 if you want. It'll just be utterly useless and a waste of your time. The only useful ones you get is from n=1n=1 and n=3n=3. If you can't see why that is the most useful ones to plug in, then you really do need to have a rest.


i guess but it can't be helped, i've tanned out these C1 and i need to do more, i can't do less, it won't help(yes yes overworking will exhaust me etc and i may not learn anything) but then again any new format of question i come across and i do i will remember and know how to do it the next time....

@uberteknik looks like your advice was good ^-^ and other ppl say the same thing too xD
Reply 10
Avatar for Zacken
Zacken
22
Original post by thefatone
i guess but it can't be helped, i've tanned out these C1 and i need to do more, i can't do less, it won't help(yes yes overworking will exhaust me etc and i may not learn anything) but then again any new format of question i come across and i do i will remember and know how to do it the next time....

@uberteknik looks like your advice was good ^-^ and other ppl say the same thing too xD


Okay.
Reply 11
Avatar for thefatone
thefatone
OP
6
Original post by Zacken
Okay.


awesome reply xD

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