Question

Find the 9th term of the arithmetic sequence.
a7 = -42 and a11 = -28; a9 = _____.

i'm not really sure how to do this :( help?

Answer 1

(a7 + a11) / 2

Answer 2

so -35?

Answer 3

yea

Answer 4

oh, because 9 is in the middle of 7 and 11??..

Answer 5

how do you figure that? :\ ...

Answer 6

yea...like 6 = 5+7 /2

Answer 7

okay..
what if it's something like, "Find the 11th term of the arithmetic sequence.
a3 = 20.5 and a8 = 13, a11 = ______." then what? :o

Answer 8

umm, use this : a(n) = a + (n-1)d

Answer 9

what numbers do i plug where in hat equation...?

Answer 10

*that

Answer 11

what's d????

Answer 12

nvm, i got it. thanks, man (: