Question

Find the 9th term of the arithmetic sequence.

a7 = -42 and a11 = -28; a9 = ____.

Answer 1

@ShadowLegendX

Answer 2

@awks

Answer 3

@tester97

Answer 4

@jim_thompson5910

Answer 5

let d be the common difference

Answer 6

a8 = a7 + d

Answer 7

a9 = a8 + d

a9 = a7 + d + d

a9 = a7 + 2d

Answer 8

a10 = a9 + d

a10 = a7 + 2d + d

a10 = a7 + 3d


see the pattern?

Answer 9

hmm sorta walk me thru it

Answer 10

what would a11 be?

Answer 11

mm 14

Answer 12

how are you getting 14

Answer 13

idk i guessed i have no clue

Answer 14

do you see how I got a8 = a7 + d ?

Answer 15

hmm u added 1

Answer 16

I took a7 and I added d

Answer 17

if you know a7 and d, you can find a8

Answer 18

then notice I wrote a9 = a8 + d

Answer 19

ahh :/

Answer 20

see how I'm getting that?

Answer 21

continue

Answer 22

so if you have any term, you add d to it to get the next term

Answer 23

say I have a10

how do I get a11 ?

Answer 24

-35

Answer 25

if you have any term, you add d to it to get the next term

Answer 26

what do you do to a10 to get a11?

Answer 27

any ideas?