Question

HELP MEDALS N FAN!!
1.)find the explicit rule for the nth term of the sequence 4, -4, 4, -4, ...

an= 4 1^(n-1)
an= 4 1^(n+1)
an= 4 (-1)^n
an= 4 (-1)^(n-1)

2.) find the explicit rule for the nth term of a geometric sequence where the second and fifth terms are 40 and 5000, respectively

an= 8 5^(n-2)
an= 8 5^(n+3)
an= 8 5^(n-1)
an= 8 5^(n+1)

Answer 1

@amoodarya @Astrophysics

Answer 2

4 *( ?) =-4
-4 *(?)= +4

Answer 3

\[4,-4,4,-4,...\\a_n=4*(-1)^{n-1}\]

Answer 4

yep thats a geometric series

Answer 5

#2??

Answer 6

@surjithayer

Answer 7

first thin find the value of the common ratio r

fifth term = ar^4 and second term = ar

ar^4 / ar = r^3

so r^3 = 5000/40

find r

Answer 8

can you do that

r^3 = 125
r = ?

Answer 9

its like 10.7

Answer 10

an= 8 5^(n-1)
is this one right

Answer 11

no
5*5*5 = 125

Answer 12

r = 5

Answer 13

oh duh

Answer 14

is it 5^(n-1)

Answer 15

now you need to find the first term which is 40/5

Answer 16

first term * 5^(n-1)

Answer 17

so i was right?

Answer 18

yes 8* 5^(n-1)

Answer 19

thank u @welshfella !!!!

Answer 20

yw