# How to solve this recurrence

1. Jul 16, 2012

### XodoX

1. The problem statement, all variables and given/known data

Solve the recurrence: T(n) = T(n/7) + T(4n/5) + n for n > 35 with base case T(n) = constant for n ≤ 35.

2. Relevant equations

3. The attempt at a solution

Is this mathematical induction? No idea how to do this one.

Last edited: Jul 16, 2012
2. Jul 16, 2012

### HallsofIvy

Staff Emeritus
You seem to be missing a "=". Where is it supposed to be?

3. Jul 16, 2012

### oli4

Hi XodoX, it does look like a recurrence, except, as HallsofIvy is pointing, the recurrence rule is missing.
Is this T(n+1)=T(n)+T(n/7)+T(4n/5)+n ? (T(36)=3c+35)
if it is, what when n is not a multiple of 7 and 4n is not a multiple of 4 ? we take the floor / ceiling ? do you have some context around this question ?

Cheers...

4. Jul 16, 2012

### XodoX

Fixed it. Sorry, wrong button.

5. Jul 16, 2012

### oli4

Still, is 36/7=5 ? is 144/5=28 ?
just to make sure we are solving the right problem, do you have some context around this puzzle ?

Cheers...

6. Jul 17, 2012

### XodoX

No, nothing else. So plug in numbers? But the equation does not hold up. I don't get it.

Last edited: Jul 17, 2012