Question

The following function defines a recursive sequence.

f(0) = -2

f(1) = 8

f(n) = -4•f(n -1) - 3•f(n - 2); for n > 1

Which of the following sequences is defined by this recursive function?

-2, 8, -26, -80, …

-2, 8, -26, 80, …

-2, 12, -44, 180, …

-2, -12, -44, -180, …

Answer 1

well you know it is one of the top two
since f1 and f2 are given... what happens when you look for f(2)? with F(0) being f(n-2) and f(1) being f(n-1)

Answer 2

so f(2) = (4*-2) - 3(8)

Answer 3

ok well obviously its -26... they both are... so next one

Answer 4

First one?

Answer 5

f(3) = 4(8)-3(-26)

what is it?

Answer 6

I'm not sure how to solve it

Answer 7

you know what i plugged in the wrong way... i said it write them typed it wrong .

-4*8 -3*(-2)=-26

Answer 8

Oh okay

Answer 9

ok
the idea with recursion is that you use the answer theat you obtain to get the next in the series

Answer 10

so of course.. mess one up... mess all the ones after it up .. lol

Answer 11

so you have the first two values in the series... f(0) and f(1) .... you are looking for f(2) f(3) ....
to fin the f(2) say n=2 so f(n-1) = f(1) NOT 1... and f(n-2)=f(0) NOT the value 0

Answer 12

So the next number will be a positive?

Answer 13

so we know f(0)=-2 f(1)=8 and now that f(2)=-26
and F(3) makes n=3 so f(n-1)=-26 and f(n-2)=8

we get f(3) = -4*(-26) -3(8)
yes it will be positive because the +104> -24
so 80

Answer 14

sorry took so long had a call