The second term of an infinite geometric sequence is 4/9, and the sixth term is 9/64. What is the sum of the first five terms of this sequence? What is the sum of all off the terms of this sequence?
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Hello, Originally Posted by cityismine The second term of an infinite geometric sequence is 4/9, and the sixth term is 9/64. a_2=4/9 a_6=9/64 we also know that a_6=a_2*q^4, where q is the constant progression. Then a_6/a_2=81/256=q^4 and : q=+ or - 3/4 Is it enough for you to continue ? (there are 2 possible answers to the following questions ^^)
Last edited by Moo; Jul 26th 2008 at 02:14 AM. Reason: pictures have disappeared
Also, you're probably gonna need this: Sum of a geometric series: Sum of an infinite geometric series: Also, to find t_1, just remember that: Like, for instance:
Thanks, I was able to take it from there and solve it. The answers I got are 781/432 and 27/64. They match the ones in the back of the book.
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