In my notes I have the expression:

with

but I can't see how we get

When I try I get

so why is

to get -3 + 4 = 1

obviously I am not understanding something...

can you point out where I am going wrong please?

Thanks

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- Oct 12th 2010, 11:55 PMdunstareccurence relations
In my notes I have the expression:

with

but I can't see how we get

When I try I get

*so why is*

to get -3 + 4 = 1

obviously I am not understanding something...

can you point out where I am going wrong please?

Thanks - Oct 13th 2010, 03:29 AMPlato
Go to this web link. You can change values for click the equals sign. You will see how the recursion changes.

Now why? Well we need to know how the initial values because we have two definiting terms. - Oct 13th 2010, 06:21 AMdunsta
That's a great link, I'm sorry but I still don't get it.

if I'm looking for f(4)

then

f(2) = 3a(2-1) + 2a(2-2)

f(2) = 3*a(1) + 2*a(0) <---- where a(1) = 2 and a(0) = 1

f(2) = 3*2 + 2*1

f(2) = 8

f(3) = 3a(3-1) + 2a(3-2)

f(3) = 3*a(2) + 2*a(1) <----a(2) = 8, a(1) =2

f(3) = 3*8 + 2*2

f(3) = 28

f(4) = 3a(4-1) + 2a(4-2)

f(4) = 3*a(3) + 2*a(2) <-----a(3)=28, a(2) = 8

f(4) = 3*28 + 2*8

f(4) = 100

is that right?

(I think I was reading too deep into things when i was trying to figure out how a(0) = 1, I guess it's just a given because a(0) =1 and a(1) = 2 are initial values, we don't need to work out how to get them, we just use them to find higher values??)

Just wandering if I have worked through this correctly or not?

Thanks for your time