SOLUTION: Find the first term of the arithmetic sequence in which, a27=-1/2 and the common difference is 2. A. 103/2 B.-105/2 C.-103/2 D.111/2

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Question 1130997: Find the first term of the arithmetic sequence in which, a27=-1/2 and the common difference is 2.
A. 103/2
B.-105/2
C.-103/2
D.111/2
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!
use the arithmetic sequence formula:
a%5Bn%5D=a%5B1%5D%2B%28n-1%29d where a%5Bn%5D is nth term, a%5B1%5D is te first term, and d is the common difference
given:
a%5B27%5D=-1%2F2=>n=27
d=2
-1%2F2=a%5B1%5D%2B%2827-1%292
-1%2F2=a%5B1%5D%2B26%2A2
-1%2F2=a%5B1%5D%2B52
-1%2F2-52=a%5B1%5D
-1%2F2-104%2F2=a%5B1%5D
a%5B1%5D=-105%2F2

so, your answer is: B.-105%2F2