# Recursie Algorithms. Is my solution ok?

1. Apr 28, 2004

### ptex

Code (Text):

This is the question I must solve;
Solve the given recurrence relation for the given inital conditions.
(This means give a formula in terms of n, not in terms of previous entries)
a[sub]n[/sub] = 7a[sub]n-1[/sub] - 12a[sub]n-2[/sub]
a[sub]0[/sub] = 3 a[sub]1[/sub] = 10
Now I am not sure what that means but I think this will solve the question

let me know if I am not even close;
Input = n
Output = X(n)

procdure find(n)
if n = 3 or n = 10 then
return (n)
return(find(n-1)+find(n-2))
end find(n)

2. Apr 28, 2004

### jamesrc

I'm fairly certain that what they are looking for is a single equation for a as a function of n. Simple example:

Given: an = an-1 + 1
and a0 = 11

Then:

an = 11+n

3. Apr 29, 2004

### ptex

Code (Text):

Solve the given recurrence relation for the given inital conditions.
(This means give a formula in terms of n, not in terms of previous entries)
a[sub]n[/sub] = 7a[sub]n-1[/sub] - 12a[sub]n-2[/sub]
a[sub]0[/sub] = 3 a[sub]1[/sub] = 10

So;
a[sub]2[/sub] = 7a[sub]2-1[/sub] - 12a[sub]2-2[/sub]
a[sub]2[/sub] = 7a[sub]1[/sub] - 12a[sub]0[/sub]
a[sub]2[/sub] = 7(10) - 12(3)
a[sub]2[/sub] = 70 - 36
a[sub]2[/sub] = 34?

4. Apr 29, 2004

### gnome

5. Apr 29, 2004

### ptex

Oh not that again I thought I was done with that. Ok I know what to do thanks again.

6. Apr 29, 2004

### ptex

I come up with all mixed fractions when I get a using the same method as I did on that problem? So that does not work.

7. Apr 29, 2004

### gnome

It works. You need to work on your algebra.