Math Problem Statement

nth term of the given arithmetic progression is the first to have 4 digits. 8, 11, 14, ... Find the value of n.

Solution

The question asks to find the first term in an arithmetic progression (AP) that has 4 digits. The given sequence is:

8,11,14,8, 11, 14, \dots

In this arithmetic progression:

  • The first term a=8a = 8
  • The common difference d=118=3d = 11 - 8 = 3

The formula for the nn-th term of an arithmetic progression is:

an=a+(n1)da_n = a + (n - 1) \cdot d

We are asked to find the value of nn such that ana_n is the first term with 4 digits. This means an1000a_n \geq 1000.

Substitute the values for aa and dd:

an=8+(n1)3a_n = 8 + (n - 1) \cdot 3

We want an1000a_n \geq 1000:

8+(n1)310008 + (n - 1) \cdot 3 \geq 1000

Now, let's solve for nn.The equation gives n=9953n = \frac{995}{3}, which is approximately 331.67. Since nn must be an integer, we round up to the next whole number, which is n=332n = 332.

Thus, the first term of the arithmetic progression with 4 digits occurs when n=332n = 332.

Do you want further clarification or details on this?

Here are 5 related questions to explore:

  1. How can I verify that n=332n = 332 is the correct value?
  2. What is the general formula for the sum of an arithmetic progression?
  3. How does changing the common difference dd affect the nn-th term?
  4. How can I find the number of terms in an arithmetic progression?
  5. What if the progression had a negative common difference?

Tip: Always remember to check whether the result for nn needs to be rounded up or down based on the problem requirements.

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Math Problem Analysis

Mathematical Concepts

Arithmetic Progression
Inequality
Algebra

Formulas

nth term of an arithmetic progression: a_n = a + (n - 1) * d

Theorems

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Suitable Grade Level

Grades 8-10