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Eelarch
Aug 23, 2009, 05:47 AM
Two sequences are generated by the recurrence relations Un+1=Aun+10 and
Vn+1=2Avn + 6
the sequences approach the same limit as n --> infinity
determine the value of a and evaluate the limit
So far I have got L=6/1-(A/2)
L=8?
galactus
Aug 23, 2009, 06:06 AM
Is this what you have?:
u_{n+1}=Au_{n}+10
v_{n+1}=2Av_{n}+6
If so, since they approach the same limit, we have L=AL+10
and L=2AL+6
Solve the system?
I do not get 8.
Eelarch
Aug 23, 2009, 06:43 AM
Would you then sue a simultanius equation to get the answer?
L=AL+10
L=2AL+6
A=4?
but if that's so then it wouldn't work because if there's a limit then -1<A<1
galactus
Aug 23, 2009, 07:02 AM
If we solve L=AL+10 for L, we get L=\frac{10}{1-A}
Sub into the second one:
\frac{10}{1-A}=2A(\frac{10}{1-A})+6
A=\frac{2}{7}
and L=14