Which of the following statements correctly determines the rule for generating the next term in the sequence 23, 19.5, 16, 12.5, . ..?

Responses

Add the common difference of −3.5

Multiply by the common ratio of −3.5

Multiply by the common difference of −3.5

Add the common ratio of −3.5

9 answers

To determine the rule for generating the next term in the sequence 23, 19.5, 16, 12.5, we can first find the difference between consecutive terms:

  • 23 to 19.5: \( 19.5 - 23 = -3.5 \)
  • 19.5 to 16: \( 16 - 19.5 = -3.5 \)
  • 16 to 12.5: \( 12.5 - 16 = -3.5 \)

We see that the difference is consistently \(-3.5\).

Therefore, we can conclude that the rule for generating the next term is:

Add the common difference of −3.5.

So, the correct response is: Add the common difference of −3.5.

Classify the following list of numbers as an arithmetic sequence, a geometric sequence, some other sequence, or not a sequence.

9, 4, −1

Responses

geometric sequence

some other sequence

not a sequence

arithmetic sequence

To classify the given list of numbers \(9, 4, -1\), we can check if it forms an arithmetic sequence or a geometric sequence.

  1. Arithmetic Sequence: In an arithmetic sequence, the difference between consecutive terms is constant.

    • From \(9\) to \(4\): \(4 - 9 = -5\)
    • From \(4\) to \(-1\): \(-1 - 4 = -5\)
    • Since the difference is the same (\(-5\)), this is indeed an arithmetic sequence.
  2. Geometric Sequence: In a geometric sequence, the ratio between consecutive terms is constant.

    • From \(9\) to \(4\): \(\frac{4}{9}\)
    • From \(4\) to \(-1\): \(\frac{-1}{4}\)
    • The ratios are not the same, so this is not a geometric sequence.

Since the sequence has a constant difference, we classify the list of numbers as an arithmetic sequence.

So the correct response is: arithmetic sequence.

What is the common ratio in the following geometric sequence?

2, 1/2 , 1/8 , 1/32 , . . .

Responses:

1/4

4

1/2

−1.5

To find the common ratio in a geometric sequence, we can divide any term by the preceding term. Let's calculate the common ratio using the first two terms of the given sequence \(2, \frac{1}{2}\):

\[ \text{Common Ratio (r)} = \frac{\text{Second Term}}{\text{First Term}} = \frac{\frac{1}{2}}{2} = \frac{1}{2} \times \frac{1}{2} = \frac{1}{4} \]

Now, let's check this ratio with the next set of terms for confirmation:

  • From \(\frac{1}{2}\) to \(\frac{1}{8}\): \[ \frac{\frac{1}{8}}{\frac{1}{2}} = \frac{1}{8} \times \frac{2}{1} = \frac{2}{8} = \frac{1}{4} \]

  • From \(\frac{1}{8}\) to \(\frac{1}{32}\): \[ \frac{\frac{1}{32}}{\frac{1}{8}} = \frac{1}{32} \times \frac{8}{1} = \frac{8}{32} = \frac{1}{4} \]

In each case, the common ratio \(r\) equals \(\frac{1}{4}\).

Therefore, the common ratio of the sequence is \(\frac{1}{4}\).

So the correct response is: 1/4.

Given the first five terms of the sequence 19, 15, 11, 7, 3 . . .
19,15,11,7,3 , use subscript notation to describe a7

Responses

a7=−4

a7=−9

a7=−5

a7=−1

To find \( a_7 \) in the sequence \( 19, 15, 11, 7, 3 \), we first need to determine the rule governing the sequence.

The sequence is decreasing, and we can calculate the difference between consecutive terms:

  • \( 19 - 15 = 4 \)
  • \( 15 - 11 = 4 \)
  • \( 11 - 7 = 4 \)
  • \( 7 - 3 = 4 \)

The common difference is \( -4 \) (we subtract \( 4 \) each time).

Using the formula for the \( n \)-th term of an arithmetic sequence: \[ a_n = a_1 + (n - 1) \cdot d \] where:

  • \( a_1 = 19 \) (the first term),
  • \( d = -4 \) (the common difference),
  • \( n = 7 \) (the term we want to find).

Now, we can substitute these values into the formula to find \( a_7 \): \[ a_7 = 19 + (7 - 1) \cdot (-4) \] \[ a_7 = 19 + 6 \cdot (-4) \] \[ a_7 = 19 - 24 \] \[ a_7 = -5 \]

Thus, the value for \( a_7 \) is \(-5\).

The correct response is: a7=−5.

Given the recursively defined formula a1=−3 , an=an−1+4 , determine which option is the correct function notation.(1 point)
Responses

f(1)=−3; f(n)=an−1+4

f(1)=−3; f(n)=f(n−1)+4

a(1)=−3; f(n)=f(n−1)+4

f(1)=−3; f(n)=f(an−1)+4

To interpret the recursively defined formula given as \( a_1 = -3 \) and \( a_n = a_{n-1} + 4 \), we need to express this correctly in function notation.

Let's analyze the responses:

  1. \( f(1) = -3; f(n) = a_{n-1} + 4 \)
    This is incorrect because \( f(n) \) should reference \( f(n-1) \), not \( a_{n-1} \).

  2. \( f(1) = -3; f(n) = f(n-1) + 4 \)
    This is correct. It represents the initial condition and the recursive definition correctly in terms of the function \( f \).

  3. \( a(1) = -3; f(n) = f(n-1) + 4 \)
    This is incorrect because it mixes \( a \) notation with \( f \) notation.

  4. \( f(1) = -3; f(n) = f(a_{n-1}) + 4 \)
    This is incorrect because it incorrectly refers to \( a_{n-1} \) instead of \( f(n-1) \).

Based on this analysis, the correct option that represents the recursive definition in function notation is:

\( f(1) = -3; f(n) = f(n-1) + 4 \).