SOLUTION: not sure why i cant find a method to do this question. the answers are:- first term =2 and r= 3/4 the question a geometric series has s subscript 3 = 37/8 and s subscripts 6

Question 760501: not sure why i cant find a method to do this question. the answers are:-
first term =2 and r= 3/4
the question
a geometric series has s subscript 3 = 37/8 and s subscripts 6 = 3367/512. find the fisrt term and the common ratio.

Answer by malglu(63) (Show Source): You can put this solution on YOUR website!
believe it or not i am answering my own question!
a) fill in the Sn formula for both given s subscript 3, and then rearrange to get a subscript 1 on one side.
b) fill in the Sn formula for s subscript 6 and then substitute the above for a subscript 1.
c) rearrange the expression to get the r's on one side. rememeber 1-r^6 is = to (1-r^3) (1+r^3). use this to cancel.
d) minus 1 on each side
e) take the cube root to get r
f) substitue this in the expression for a subscript 1 to get a subscript 1.

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