Question

Find f(5) for this sequence:
f(1) = 2 and f(2) = 4, f(n) = f(1) + f(2) + f(n - 1), for n > 2.

f(5) = (2 points)

Answer 1

@Luigi0210 @agent0smith

Answer 2

@alassen

Answer 3

@ganeshie8

Answer 4

this is going to take few steps

Answer 5

f(n) = f(1) + f(2) + f(n - 1)

Answer 6

O crap lmao

Answer 7

you want to find f(5),
so plugin n = 5 above ^

Answer 8

yes :)

Answer 9

f(n) = f(1) + f(2) + f(n - 1)

f(5) = ?

Answer 10

f(5) = f(1) + f(2) + f(5-1)
= 2 + 4 + f(4)
= 6 + f(4)

Answer 11

do we knw f(4) yet ?

Answer 12

20?

Answer 13

O my gosh don't think im stupid

Answer 14

lets find out

Answer 15

but before diving in to find f(4),
just save wat we have till now, so that we can come back here once we find f(4) :-

f(5) = 6 + f(4) ------------------------------------- (1)

Answer 16

we wil get back to this equation (1), after finding f(4), okay ?

Answer 17

ummm okay

Answer 18

f(n) = f(1) + f(2) + f(n - 1)

we want to find f(4), so we plugin n = 4 :-

f(4) = ?

Answer 19

16?

Answer 20

f(4) = f(1) + f(2) + f(4-1)
= 2 + 4 + f(3)
= 6 + f(3)

Answer 21

we're not that lucky yet ;)

Answer 22

so, we got

f(4) = 6 + f(3) --------------------------------(2)

Answer 23

since we dont knw f(3) yet,
we need to find f(3) value first, and get back to this equation, okay ?

Answer 24

u still wid me ha

Answer 25

Yeah I think so......

Answer 26

good :)

lets find f(3) :-

f(n) = f(1) + f(2) + f(n - 1)

plugin n = 3

f(3) = f(1) + f(2) + f(3-1)
= 2 + 4 + f(2)
= 2 + 4 + 4
= 10

Answer 27

looks we're done.
we got f(3) = 10,
so we can go back to 2nd equation and plug this f(3) = 10 value

Answer 28

What there's more O boy!!!

Answer 29

remember we saved two equations before

Answer 30

go back to 2nd equation, and plugin f(3) = 10

Answer 31

that gives u f(4) value

Answer 32

f(4) = 6 + f(3) --------------------------------(2)

f(4) = 6 + 10 = 16

Answer 33

plug this f(4) = 16 in equation (1)

Answer 34

f(5) = 6 + f(4) ------------------------------------- (1)

Answer 35

f(5) = 6 + 16 = 22

Answer 36

we're done.

Answer 37

Wow I actually kind of got all that toward the end thank you I wish I knew all that so I wouldn't need help lol thanks again :)

Answer 38

glad to hear that :) im sure if u do one more problem like this u wil feel more confident... :)

Answer 39

:) thank you

Answer 40

np.. u wlc :)