Question

Find f(5) for this sequence:

f(1) = 2 and f(2) = 3, f(n) = f(1) + f(2) + f(n - 1), for n > 2.

f(5) = ______

Numerical Answers Expected!

Answer 1

it is 22

Answer 2

Can you explain how? for future reference?

Answer 3

Directly substitute n = 5 into the formula.

f(5) = f(1) + f(2) + f(4) .. Keep this in mind. We know f(1) = 2, and f(2) = 4 so

f(5) = 2 + 4 + f(4) = 6 + f(4). Now determine f(4) . . .

f(4) = f(1) + f(2) + f(3) = 6 + f(3)... so..

f(5) = 6 + (6 + f(3) ) = 12 + f(3)

Answer 4

Here is the general rule: f(n) = f(1) + f(2) + f(n - 1)

Answer 5

We also know the value of f(1) and f(2). f(1) = 2, f(2) = 4. So we can rewrite f(n) as..

f(n) = 2 + 4 + f(n -1) = 6 + f(n - 1).

Answer 6

You said f(2) = 4 but it says in the problem that f(2) = 3 ?????

Answer 7

See if you can now determine f(3) knowing that f(n) = 6 + f(n - 1)

Answer 8

oh, my mistake

Answer 9

one moment then

Answer 10

So we have the conditions:
f(1)=2f(2)=3f(n)=f(1)+f(2)+f(n−1);n>2

We can simplify f(n) to:
f(n)=5+f(n−1)

So therefore:
f(5)=5+f(5−1)=5+f(4)=5+[5+f(3)]=5+[5+(5+f(2))]=5+5+5+3=18

Answer 11

You have the following sequence of numbers leading up:
f(n)=5+f(n−1);n>2f(1)=2f(2)=3f(3)=8f(4)=13f(5)=18

Answer 12

its 22

Answer 13

no, it is 18

Answer 14

Thanks! And do you mind answering one more problem???

Answer 15

oh sorry

Answer 16

suree :3

Answer 17

f(1) = 0 and f(2) = 1, f(n) = f(n - 1) + f(n - 2), for n > 2.

0, -1, 1, 0, 2

0, 1, 1, 2, 3

0, 1, 2, 2, 3

0, 1, 1, 2, 2

Answer 18

Generate the first 5 terms of this sequence:

Answer 19

I am absolutely lost on this one

Answer 20

in what order?

Answer 21

ascending or descending?

Answer 22

Ascending I assume

Answer 23

You there?

Answer 24

f(5) = f(4) + f(3)
You have to figure out f(3) first.
Then figure out f(4)
Then figure out f(5)...the 5th term

Answer 25

Where does it say f(5) ?

Answer 26

It's the fifth term, find it using that ^

0, 1, 1, 2, 3

Answer 27

Thanks!!!

Answer 28

each number in the sequence is the sum of the previous two

Answer 29

medal please?

Answer 30

I did...

Answer 31

o otay thanks :3