9.1-9.3 sequences and series

Question 1

geometric explicit sequences

Answer 1

an = (a1)r^n-1

Question 2

geometric recursive sequence

Answer 2

an = r(an-1)

Question 3

arithmetic recursive sequence

Answer 3

an = a +d

n-1

Question 4

1st term is positive

Answer 4

(-1)^n+/-1

Question 5

distinguishable permutations

G R A S S

Answer 5

order matters
taking all elements
set contains indistinguishable elements

5!/ 1! 1! 1! 2! 2!

Question 6

summation notation alligator teeth face?

Answer 6

right

Question 7

subset where order doesn’t matter

Answer 7

nCr

n!/(n-r)! r!

Question 8

arithmetic explicit sequence

Answer 8

an = dn + a0

Question 9

permutation

Answer 9

order matters
taking all elements

n!

Question 10

5,6,7,8…

what does “…” mean?

Answer 10

infinite

s = a1/1-r
infinity

Question 11

subset where order matters

Answer 11

nPr

n!/(n-r)!

Question 12

combination

Answer 12

order doesn’t matter

taking all elements

Question 13

arithmetic sum of a series

Answer 13

sn = n/2(a1 + a2)

or an idk?!!!

Question 14

recursive sequence

Answer 14

provide number equals as part of definition

example: a1 = 4
in addition to the actual equation

Question 15

1st term negative

Answer 15

(-1)^n

Question 16

recursive formula

Answer 16

n is in subscripts only

Question 17

sum of a series geometric

Answer 17

sn = a1(1-r^n/1-r)

Question 18

Binomial solver with nCr

(x+6)^13

Answer 18

n = power

r =power of term minus 1

     C
13    3

Question 19

Which has a greater amount of possible answers

Permutation or combination?

Answer 19

Permutation because with combination order doesn’t matter so 123 231 321 all count as the same thing (1)

Question 20

What is “i”

Answer 20

First value of sequence

Usually i equals 1

Question 21

Find first 4 terms of sequence

Answer 21

Use previous term as “an” to find the next term

Question 22

Partial sum arithmetic sequence

Answer 22

an = n/2(a1 + an)