Question

The following function defines a recursive sequence.
f(0) = -5

f(1) = 20

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

Which of the following sequences is defined by this recursive function? (4 points)


-5, -20, -65, -200, …
-5, 20, -92, 372, …
-5, -24, -92, -372, …
-5, 20, -65, 200, …

Answer 1

@DanJS @zepdrix

Answer 2

@3mar

Answer 3

\[\large\rm f(\color{orangered}{n})=-4\cdot f(\color{orangered}{n}-1)-3\cdot f(\color{orangered}{n}-2)\]
So umm.. you should be able to eliminate one of your options immediately.
If our first term is -5, and the next is 20,
you can ignore the list that doesn't start with -5 and 20.

Answer 4

Plug in n=2 to find the third term of your sequence,\[\large\rm f(\color{orangered}{2})=-4\cdot f(\color{orangered}{2}-1)-3\cdot f(\color{orangered}{2}-2)\]\[\large\rm f(\color{orangered}{2})=-4\cdot f(1)-3\cdot f(0)\]

Answer 5

They gave you the values for f(0) and f(1).
So plug them in and simplify.

Answer 6

whaaa

Answer 7

this is so confusing

Answer 8

This is so easy!

The first term is -5
The second term is 20

Any choice does not match these two criteria is excluded!

Is it clear so far?

Answer 9

what other choices are there?

Answer 10

-5, -20, -65, -200..........×
-5, 20, -92, 372.............may be
-5, -24, -92, -372...........×
-5, 20, -65, 200.............may be

Answer 11

oh okay so we can eliminate C

Answer 12

and A

Answer 13

Congratulations!

Answer 14

@zepdrix
Please proceed!

Answer 15

Where are you guys?

Answer 16

oh sorry im back

Answer 17

So Are you satisfied?

Answer 18

yes

Answer 19

he wont come back i think so you will have to do next steps

Answer 20

@3mar can we work on this together quickly

Answer 21

Pleasure is mine!

Answer 22

Yes, can you?

Answer 23

yes wait 2 min

Answer 24

please thanks

Answer 25

As @zepdrix said and mentioned:

\[\large\rm f(\color{orangered}{2})=-4\cdot f(\color{orangered}{2}-1)-3\cdot f(\color{orangered}{2}-2)\]

\[\large\rm f(\color{orangered}{2})=-4\cdot f(1)-3\cdot f(0)\]

Answer 26

Ca you find out the third term!?

Answer 27

@3mar sooo sorry