Math Problem Statement

Terms in a sequence are given by sₙ = 4n + 7, for n = 0, 1, 2, 3, ... Which of the following describes the sequence? A) The sequence is geometric with an initial value of 7 and a common ratio of 4. B) The sequence is geometric with an initial value of 11 and a common ratio of 4. C) The sequence is arithmetic with an initial value of 7 and a common difference of 4. D) The sequence is arithmetic with an initial value of 11 and a common difference of 4.

Solution

Let us analyze the given sequence and solve the problem.

The sequence is defined by the formula:

sn=4n+7,for n=0,1,2,3,s_n = 4n + 7, \quad \text{for } n = 0, 1, 2, 3, \dots

Step 1: Identify the type of sequence

  • A geometric sequence has a constant ratio between consecutive terms.
  • An arithmetic sequence has a constant difference between consecutive terms.

Let us calculate the first few terms of the sequence by substituting values of nn:

s0=4(0)+7=7,s1=4(1)+7=11,s2=4(2)+7=15,s3=4(3)+7=19s_0 = 4(0) + 7 = 7, \quad s_1 = 4(1) + 7 = 11, \quad s_2 = 4(2) + 7 = 15, \quad s_3 = 4(3) + 7 = 19

The differences between consecutive terms are:

s1s0=117=4,s2s1=1511=4,s3s2=1915=4s_1 - s_0 = 11 - 7 = 4, \quad s_2 - s_1 = 15 - 11 = 4, \quad s_3 - s_2 = 19 - 15 = 4

Since the difference is constant, the sequence is arithmetic with a common difference of 44.

Step 2: Initial Value

The initial value (s0s_0) is 77.

Conclusion

The sequence is arithmetic with an initial value of 77 and a common difference of 44. Thus, the correct answer is:

C: The sequence is arithmetic with an initial value of 7 and a common difference of 4.\boxed{\text{C: The sequence is arithmetic with an initial value of 7 and a common difference of 4.}}


Do you want further explanation or more examples? Let me know!

Related Questions:

  1. How do you distinguish between arithmetic and geometric sequences?
  2. What is the general formula for the nn-th term of an arithmetic sequence?
  3. Can an arithmetic sequence ever have a constant ratio between terms? Why or why not?
  4. How would the formula change if the sequence started at s0=11s_0 = 11?
  5. How can you graph the sequence sn=4n+7s_n = 4n + 7 and interpret it visually?

Tip:

When analyzing sequences, always calculate a few terms and their differences or ratios to determine the type of sequence.

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Math Problem Analysis

Mathematical Concepts

Arithmetic Sequences
Linear Sequences

Formulas

sₙ = a + (n-1)d
sₙ = 4n + 7

Theorems

Definition of Arithmetic Sequence

Suitable Grade Level

Grades 8-10