Question

the third term of an arithmetic sequence is 14, and the ninth term is -1. Find the first four terms

Answer 1

ahh tricky problem.. first solve what you are given.. assume that 14 is A1

so An = A1 + (n-1)d

A1 = 14
An = -1
n = ?
you wanna know d...

but...what is n? how many numbers are in the series from the 3rd term to the 9th term?

Answer 2

i dont know, thats my problem too. that was just the problem said on the paper

Answer 3

hahaha =))) let's count...

3rd term
4th term
5th term
6th term
7th term
8th term
9th term

how many terms do you see?

Answer 4

oh, LOL. 7

Answer 5

yes! so n = 7...solve for the common difference...show me :D

Answer 6

wait, so is it okay to put a3 in the equation in the a1 spot?

Answer 7

we will assume..there are two equations here...we will first solve for the d and assume that A1 = 14 so...A7 = -1 n =7

Answer 8

ohh okay. thank you!