# math

in a certain geometric sequence, the third term is 8 and the sixth term is 125. what is the first term?

1. 👍 0
2. 👎 0
3. 👁 36
1. ar^2 = 8
ar^5 = 125

divide the 2nd by the 1st ....
r^3 = 128/8
r = 5/2

back into the first
a(25/4) = 8
etc.

1. 👍 0
2. 👎 0
posted by Reiny

## Similar Questions

1. ### math

in a certain geometric sequence, the third term is 8 and the sixth term is 125. what is the first term?

asked by deborah on July 22, 2011
2. ### algebra1

Which of the following functions represents a geometric sequence? Why? Answer Choices The function f(x)=x7 represents a geometric sequence because each term is raised to the seventh power to make it greater. The function f(x)=7x

asked by miyah on October 9, 2017
3. ### Algebra

I am so lost on these problems. Write a geometric sequence that starts with 3 and has a common ratio of 5. What is the 23rd term in the sequence. Write an arithmetic sequence that has a common difference of 4 and the eighth term

asked by Randy on June 17, 2016
4. ### Math

1. The fourth and seventh terms of a geometric sequence are 6 and 384, respectively. What is the common ratio and the sixth term of the sequence? 2. The fifth and eight terms of a geometric sequence of real numbers are 7! and 8!

asked by Penny on March 13, 2015
5. ### maths

given 1,0.5,4,o.25,7,0.125,10 assume this pattern continues consistently 1.write down the 33th term in this sequence 2.determine the sum of the first 24 terms in this sequence.give the answer to five decimal place 2.1.in a

asked by memory on February 15, 2015
6. ### math

the third term of a geometric sequence is t3= -75 and the sixth term is t6= 9375. determine the first term and the common ratio

asked by liza on January 4, 2011
7. ### maths

the third term of a geometric sequence is 6 and the sixth term is 3 over 32. Determine the first terms and the general term Tn?

asked by bahle on January 23, 2014
8. ### Sj

Mathematics......Under number patterns-Geometric series If a question goes.determine the expression for the nth term of the following sequence if the a) 4th term is 24 and the 7th term is 192 in a geometric sequence.what formula

asked by Mahlogonolo on July 16, 2015
9. ### Math

1. What is the tenth term of the geometric sequence whose first term (a1) is 16 and the common ratio (r) is –½? 2. Given the terms a10 = 3 / 512 and a15 = 3 / 16384 of a geometric sequence, find the exact value of the first

asked by Jade on June 18, 2014
10. ### Math

The 1st term of a geometric sequence is 25 and the 6th term is -1/125. What is the 3rd term?

asked by Melissa on November 22, 2015

More Similar Questions