Question

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

-15, -6, 3, 12, ...

Answer 1

please explain how you got it

Answer 2

can you find the common difference of that given series?

or know what common difference is?

Answer 3

9 @hartnn

Answer 4

thats correct!

Answer 5

so just use this formula

\(\Large a_n = a_1 + (n-1)d\)

where d = common difference = 9
a1 = 1st term = -15

plug these values in, and tell me what u get :)

Answer 6

so an= -15 + 9(n-1)?

Answer 7

good!
now simplify that.

distribute 9 to (n-1)

Answer 8

9n-9?

Answer 9

oh ok i got it, Thank you!

Answer 10

can you help with summation though? ill open another question

Answer 11

yes,
then we had -15
so finally,
\(\large a_n = 9n-24\)

welcome ^_^

and sure, open another question :)