Question

How do i write a recursive formula for the explicit formula?
A(n)=5+(n-1)(-7).
Answer Choices:
1.A(n)=A(n-1)+5;A(1)=-7
2.A(n) A(n-1)-7;A(1)=5
3.A(n-1)=A(n)-7;A(1)=5
4.A(n-1)=A(n)+5; A(1)=-7
Which one should i choose?

Answer 1

I don't know.

Answer 2

I need to help with figuring out the correct answer. what is the first steps i take to solve this problem?

Answer 3

You typed the wrong equation, I guess.

Answer 4

Can you explain why that's the correct answer?

Answer 5

It should be \(A_n = 5+A_{n-1}(-7)\)

Answer 6

No, on my homework its says what i typed on here correctly.

Answer 7

Can you scan and post the original one?

Answer 8

for recursive and explicit formula, need know the right one to solve.

Answer 9

I don't have a scanner

Answer 10

I can draw the formula.

Answer 11

ok, the very first formula, not the answer choices.

Answer 12

This is exactly what it looks like

Answer 13

I'm sorry that's the best i can draw it or show to you. It is a explicit formula so it has paratheses not powers.

Answer 14

\(A_n = 5 +(n-1)(-7)\)
if n=, then \(A_1= 5 +(1-1)(-7) =5\) ok?

Answer 15

if n=1 sorry about that :)

Answer 16

Need you confirm whether you understand step 1 or not

Answer 17

I understand.

Answer 18

so, we have only 2 options b or c, right?

Answer 19

no i have 4 answer options

Answer 20

It could be B your right.

Answer 21

but for 1and 4, it gives us \(A_1=-7\) hence get rid of them, right?

Answer 22

so i slash out all the other answers?

Answer 23

sure

Answer 24

Okay that makes sense.

Answer 25

now, between 2, 3 we test one by one. If you are lucky enough, you get the answer at the first test

Answer 26

okay how do you do that?

Answer 27

Explain.

Answer 28

for 2) it says \(A_n = A_{n-1} -7\) and \(A_1=5\) right?

Answer 29

Yes.

Answer 30

now, if n =2, then n-1 =1, so \(A_2= A_1 -7= 5 -7 =-2\) ok?

Answer 31

Okay.

Answer 32

Let test
\(A_n = 5 + (n-1) (-7) \\
A_2= 5 +(2-1)(-7) = -2\)
Ah ha!!

Answer 33

Is that the correct answer?

Answer 34

one more!! if n=3?
apply the second option: \(A_n = A_{n-1}-7\\A_3=A_2-7 = -2-7=-9\)
Apply the given equation: \(A_n = 5+(n-1)(-7)\\A_3= 5+(3-1)(-7)=5+2(-7) =5-14=-9\)
Wow... it works, right?
That is the way you work to figure out what it the right answer

Answer 35

where did you get n=3?

Answer 36

just apply n=1, 2, 3, ..... to get arbitrary \(n^{th}\) term.

Answer 37

this is the order of the sequence, like you have a line of people and you name the first one is A1, the second one is A2, the third one is A3.....