Question

nth terms again

Answer 1

Find an equation for the nth term of the arithmetic sequence.

a19 = -92, a20 = 6

Answer 2

i didnt know if putting lil v symbols to indicate that there going down would be confuing or not... so its basically like ^ except the opposite c: so av19=-92,av20=6

Answer 3

like theyre acting as downward arrows XD

Answer 4

hehe
you have 20th term and 19th term
so d will be 6-(-92)
which is 98

Answer 5

where D is common difference

Answer 6

\[a_{19}=-92, a _{20}=6\]

Answer 7

yes i got it
now we have to find the first term

Answer 8

so im just adding 98 every time?

Answer 9

so we have 6 = a + 98(19)

Answer 10

yep

Answer 11

an = -1856 + 98(n - 1)
an = -1856 - 98(n - 1)
an = -1856 - 98(n + 1)
an = -1856 + 98(n + 1)

these are much more complicated than they need to be.... i would understand more if it just said +98 if you increasing -98 if your decreasing XD

Answer 12

haha
the answer is A :)

Answer 13

you know how
fits the formula

Answer 14

Find the sum of the geometric sequence.

1/3, 2/3, 4/3, 8/3, 16/3
i think i can do this one XD cuz its just adding
itd be 31/3 right?

Answer 15

hahaha
yes yes
but there is formula for geometric sum too

Answer 16

a*(1-r^n/1-r)

Answer 17

but its adding c:

Answer 18

haha xD
yes yes