Question

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

a19 = -58, a21 = -164

Answer 1

@amistre64 do you mind helping me with this one too? would I use the formula an=dn+c?

Answer 2

something simliar yes

Answer 3

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

Answer 4

let a1 = a19, then a3 = a21

Answer 5

-164=-58 +d(3-1); solve for d

Answer 6

so -53?

Answer 7

yes

therefore:

a19 = a1 -53(18); solve for a1

Answer 8

ahh okay 896

Answer 9

therefore:

an = 896 -53(n-1)

Answer 10

Okay awesome! thank you for the right formula!

Answer 11

yep