SOLUTION: The 3rd term of an arithmetic sequence is 34 and the 15th term is -14. Determine the first 2 terms of the squence

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Question 1070901: The 3rd term of an arithmetic sequence is 34 and the 15th term is -14.
Determine the first 2 terms of the squence
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
a%5B3%5D=34
a%5B1%5D%2B%283-1%29%2Ad=34
1.a%5B1%5D%2B2d=34
.
.
.
a%5B15%5D=-14
a%5B1%5D%2B%2815-1%29%2Ad=-14
2.a%5B1%5D%2B14d=-14
.
.
.
Subtracting 1 from 2,
a%5B1%5D%2B14d-a%5B1%5D-2d=-14-34
12d=-48
d=-4
So then,
a%5B1%5D%2B2%28-4%29=34
a%5B1%5D-8=34
a%5B1%5D=42
So,
a%5Bn%5D=42%2B%28n-1%29%28-4%29
a%5Bn%5D=42-4n%2B4
a%5Bn%5D=46-4n
So now use this to find the first two terms.