Question

In: Computer Science

For the following exercises, find the specified term for the geometric sequence, given the first four terms. an = {−1, 2, −4, 8, ...}. Find a12.

For the following exercises, find the specified term for the geometric sequence, given the first four terms. 

an = {−1, 2, −4, 8, ...}. Find a12.

Solutions

Expert Solution

Consider the following geometric sequence:

{=1, 2, -4, 8} ...... (1)

 

The first term of above sequence is a1 = -1.

 

Common ratio of the above sequence will be obtained by dividing its second term by the first term,

r = a2 ÷ a1

   = 2 ÷ (-1)

   = -2

 

Use the formula for nth term of a geometric sequence,

an = a1 × r(n-1) ...... (2)

 

Substitute a1 = 1, n = 12 and r = -2 in formula (1) and compute 12th term of the sequence,

a12 = (-1) × (-2)(12-1)

        = (-1) × (-2)11

       = (-1) × (-2048)

       = 2048

 

Therefore, 12th term of the above geometric sequence is a12 = 2048.


Therefore, 12th term of the above geometric sequence is a12 = 2048.

Related Solutions

For the following exercises, write the first five terms of the geometric sequence, given the first term and common ratio. a1 = 5, r = 1/5
For the following exercises, write the first five terms of the geometric sequence, given the first term and common ratio. a1 = 5, r = 1/5
For the following exercises, find the specified term given two terms from an arithmetic sequence. a1 = 33 and a7 = −15. Find a4 .
For the following exercises, find the specified term given two terms from an arithmetic sequence. a1 = 33 and a7 = −15. Find a4 .
For the following exercises, write the first four terms of the sequence.
For the following exercises, write the first four terms of the sequence.
Given the geometric sequence an = 4n . Find the first three terms and the common...
Given the geometric sequence an = 4n . Find the first three terms and the common ratio.
For the following exercises, find the common ratio for the geometric sequence.
For the following exercises, find the common ratio for the geometric sequence.
Find the first four terms of the sequence (an)n≥1 with the given definition. Determine if they...
Find the first four terms of the sequence (an)n≥1 with the given definition. Determine if they are potentially arithmetic or geometric. (a) an is the number of n-bit strings which have more 1’s than 0’s. (Also, write down the strings for n ≤ 4.) (b) an is the number of n-bit strings in which the number of 1’s is greater than or equal to the number of 0’s in every prefix. For example, 010111 would not qualify, since the prefix...
What are the first five terms of the geometric sequence a1 = 3, an = 4 ⋅ an − 1 ?
What are the first five terms of the geometric sequence a1 = 3, an = 4 ⋅ an − 1?
For the following exercises, use the formula for the sum of the first n terms of each geometric sequence, and then state the indicated sum.
For the following exercises, use the formula for the sum of the first n terms of each geometric sequence, and then state the indicated sum.
For the following exercises, write the first eight terms of the sequence.
For the following exercises, write the first eight terms of the sequence.
For the following exercises, write the first eight terms of the sequence.
For the following exercises, write the first eight terms of the sequence.
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT