Find the nth Term Formula for Sequence: 7, 11, 15, 19, 23

Question

Given the series whose difference between two jumped numbers is constant:

7,11,15,19,23 7,11,15,19,23

Describe the property using the variable n n

Video Solution

Solution Steps

00:00 Find the sequence formula
00:04 This is the first term according to the given data
00:11 Let's observe the change between terms (D) according to the given data
00:28 This is the constant difference in the sequence (D)
00:33 Let's use the formula to describe the sequence
00:40 Let's substitute appropriate values and solve to find the sequence formula
00:48 And this is the solution to the question

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Identify the first term and the common difference.
  • Step 2: Use the arithmetic sequence formula to express the series.
  • Step 3: Construct the formula based on the calculations.

Now, let's work through each step:
Step 1: The first term a1a_1 of the series is 77. Calculate the common difference dd as the difference between two consecutive terms. Between 77 and 1111, the difference is 44, and this holds for each consecutive pair of terms. Thus, d=4d = 4.

Step 2: We'll use the formula for the nn-th term of an arithmetic sequence, which is a(n)=a1+(n1)×da(n) = a_1 + (n-1) \times d.

Step 3: Substitute the values for a1a_1 and dd into the formula:
a(n)=7+(n1)×4a(n) = 7 + (n-1) \times 4.

Therefore, the solution to the problem is a(n)=7+(n1)×4 a(n)=7+(n-1)\times4 .

Answer

a(n)=7+(n1)×4 a(n)=7+(n-1)\times4