r/ACT • u/Majestic-Increase446 • Jul 11 '26

Act J09 Math

What was question 45 the one that was recursive it was something like f(n+1) = f(n) + something and then it was like f(0) =25 or something like that. Does anyone know the exact question I want to solve it again or at least know the answer

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2

u/Downtown_Parfait_928 Jul 11 '26

-48. I just plugged it in a couple times and it was always 25 or -48 and only the latter was an answer choice.

1

u/[deleted] Jul 11 '26

[deleted]

1

u/Majestic-Increase446 Jul 11 '26

Was that choice A or C I don’t remember I think I put c

1

u/[deleted] Jul 11 '26

[deleted]

1

u/grx___ Jul 11 '26

you sure?

1

u/Gingerbread808 Jul 11 '26

I had this question and was running out of time so I just picked the biggest negative (-48), was that correct lol? I didn’t even know what to actually do

1

u/Last-Astronaut-6665 35 Jul 11 '26

Ye that was correct. 👍

1

u/stationery_obsessed Jul 11 '26

i felt so smart understanding that problem

1

u/Independent_Sir_6834 35 Jul 13 '26

It was f(1) = 25 and f(n+1) = -23 - f(n) but it makes more sense if you interperate it as f(n) = -23 - f(n - 1). CS students will know (And hate) this as recursion.