Question

Ill award medlas :) Find an equation for the nth term of the arithmetic sequence. Need some verification and help.
a16 = 21, a17 = -1

an = 351 - 22(n - 1)
an = 351 + 22(n + 1)
an = 351 + 22(n - 1)
an = 351 - 22(n + 1)

Answer 1

I got C

Answer 2

those are answer choices?

Answer 3

@dirtyblondezzz its not C....

Answer 4

yeah those are the choices

Answer 5

first off all find the first term i.e a_1 and the common difference "d"

Answer 6

and after tht
\[a_n = a_1 + (n - 1)d\]

Answer 7

okay so what would i plug in

Answer 8

plug \[a_1 \] and d

Answer 9

i just dont know what the number would be to plug in

Answer 10

see u got a_16 and a_17
\[a_{16} = a_1 + (16 - 1)d\]
\[a_{17} = a_1 + (17 - 1)d\]

Answer 11

okay i see continue

Answer 12

so \[21 = a_1 + 15d \]
and \[-1 = a_1 + 16d \]
solve these equations and get a_1 and d

Answer 13

im a bit confused would you mind showing me @rishavraj

Answer 14

can u solve those equations????and get a_1 and d /????

Answer 15

no lol

Answer 16

do it by elimination method.......
multiply 2nd equation by -1 and add both equations

Answer 17

i got answer choice D now but when I did the elimination method Im just not sure if i got it right. idk lol

Answer 18

@rishavraj

Answer 19

how it could be (n + 1) ???????o_)

Answer 20

i did the elimination method and mathway gave me d=-20 idek lol

Answer 21

hmm let me do this again hold on

Answer 22

okay so i know its not an equation that consists of (n+1) and when i re did my equation and sub- it gave me answer choice A! Im pretty sure i got it right this time lol

Answer 23

d = -22 -_-

Answer 24

and yeah its A.....

Answer 25

i was close lol! yeah idk I think i subbed the wrong numbers lol i always had problems with elimnation and stuff but thank you for your help :))))) @rishavraj #impartindiantoo :) haha my stepdads names raj #random but anyway thank you :)!!

Answer 26

huh ur stepdads name is raj???o_O

Answer 27

yeah haha xD @rishavraj

Answer 28

oooo lol...xD