# math

posted by .

Is there a common ratio for the geometric sequence and what are the missing terms?

16,40,100,?,?

IS there a common ratio for the geometric sequence and what are the missing terms?

81,54,?,?,?

• math -

Yes, and 2.5 is the ratio. Following terms are 150, and 225.

For the second question, try 2/3 for the ratio. 36, 24, ...
With only two terms, one really can't say if there is a "common" ratio. There are no other pairs to compare.

• math -

if the given sequence is a geometric sequence, then it follows the formula
A,n+1 = r*(A,n)
where
r = ratio between two consecutive terms
A,n = the nth term
A,n+1 = the term after A,n

substituting the first and second term,
40 = r*16
r = 40/16
r = 2.5
to check, let's see if we would obtain 100 if we multiply 40 by the ratio=2.5
40*2.5 = 100
to find the next term after 100, we just multiply by the ratio,, thus the next two terms are:
100*2.5 = 250
250*2.5 = 625

for the second question, if it's a geometric sequence, then it follows the formula above. thus, getting the ratio,
54 = r*81
r = 54/81
r = 2/3
to get the next three terms, we multiply the next terms by 2/3:
54*(2/3) = 36
36*(2/3) = 24
24*(2/3) = 16

hope this helps~ :)

## Similar Questions

1. ### Algebra

Need to get these problems checked-- 31. Determine whether the sequence 7, 21, 35, 49 is geometric. If so, find its common ratio. a. no b. yes, common ratio of 14 c. yes, common ratio of 12 I'm stuck between A and B.. 32. What are …
2. ### Math

A sequence is formed by adding together the corresponding terms of a geometric sequence and and an arithmetic sequence.The common ratio of the geometric sequence is 2 and the common difference of the arithmetic sequence is 2.The first …
3. ### Math

first three terms of a geometric sequence are the same as the 1st, 9th and 11th terms of an arithmetic sequence, respectively. What is the common ratio in the geometric sequence ?
4. ### Can someone help me?!

The 1st, 5th and 13th terms of an arithmetic sequence are the first three terms of a geometric sequence with a common ratio 2. If the 21st term of the arithmetic sequence is 72, calculate the sum of the first 10 terms of the geometric …
5. ### Maths

Eric thinks of 2 sequences.One is geometric and the other arithmetic.Both sequences start with the number 3.The common ratio of the geometric sequence is the same as the common difference of the arithmetic sequence.If the 6-th term …
6. ### Maths

1..The first 2 terms of a geometric progression are the same as the first two terms of an arithmetic progression.The first term is 12 and is greater than the second term.The sum of the first 3 terms od the arithmetic progression is …
7. ### MATH

A new sequence is formed by adding together the corresponding terms of a geometric sequence and an arithmetric sequence. the geometric sequence has a common ratio of 3 and the arthmetric sequence has a common difference of -2. The …
8. ### pre-calculus urgent

Please help me here as well to clarify more my understanding. Let a1, a2, a3, . . . be a geometric sequence with initial term a and common ratio r. Show that a1^2, a2^2, a3^2, . . . is also a geometric sequence by finding its common …
9. ### Math

Is there a common ratio for the geometric sequence and what are the missing terms?
10. ### Algebra 2

Is there a common ratio for the geometric sequence and what are the missing terms?

More Similar Questions