Question

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

a15 = -53, a16 = -5

Answer 1

what is the difference d between two terms in the sequence ?

Answer 2

48?

Answer 3

correct
now the formula for the nth term in arithmetic sequence is:
an = a1 + (n-1)d

can you find a1 ?

Answer 4

I know its -725 i think but is that it?

Answer 5

so lets check, lets plug a16 (or a15) into the formula:
a16 = a1 + (16-1)*48
a1 = a16 - 15 * 48 = -725

so it is correct

Answer 6

so now plug a1 and d into the formula for an
and done :)

Answer 7

so would the equation be an=-725 +48(n-1)?

Answer 8

yes !
you can always verify it by plugging n=15 or 16 and check if you get the given values
a15 = -725 + 48 * 14 = -53
so it is correct indeed

Answer 9

(this is a good check to do in a test for example.. you can see if your answer is good or not)

Answer 10

Thank you so so much! You have NO idea how much you have helped me

Answer 11

yw :)