SOLUTION: The ninth term of the arithmetic sequence is 1/6 ; the sixteenth term is 2 ½. Find the first term.

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Question 575136: The ninth term of the arithmetic sequence is 1/6 ; the sixteenth term is 2 ½. Find the first term.
Answer by chana(69) About Me  (Show Source):
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The ninth term of the arithmetic sequence is 1/6 ; the sixteenth term is 2 ½. Find the first term.
sol:
taking it as Arithmetic progression we can get 2 eqn based on this formula : a +(n-1)d.. where a= first term , d = common difference , n = position of the term
a+8d=1/6
a+15d=5/2
solving this, a= (-5/2)