Math Problem Statement

Find the common difference of the arithmetic sequence with a4=10 and a11=45

Solution

To find the common difference of an arithmetic sequence, we use the formula for the nth term of an arithmetic sequence:

an=a1+(n1)da_n = a_1 + (n-1) \cdot d

where:

  • ana_n is the nth term,
  • a1a_1 is the first term,
  • dd is the common difference,
  • nn is the term number.

We are given:

  • a4=10a_4 = 10,
  • a11=45a_{11} = 45.

Using the formula for both the 4th and 11th terms, we have:

a_4 = a_1 + 3d = 10 \tag{1} a_{11} = a_1 + 10d = 45 \tag{2}

Now, subtract equation (1) from equation (2) to eliminate a1a_1 and solve for dd:

(a1+10d)(a1+3d)=4510(a_1 + 10d) - (a_1 + 3d) = 45 - 10

Simplifying:

7d=357d = 35

d=357=5d = \frac{35}{7} = 5

So, the common difference dd is 5.

Do you want further details on the steps or have any other questions?

Here are 5 related questions:

  1. How do you find the first term a1a_1 in this sequence?
  2. How do you find the nth term of an arithmetic sequence?
  3. What is the sum of the first 11 terms in this sequence?
  4. How would you determine the common ratio of a geometric sequence?
  5. How do arithmetic sequences relate to linear equations?

Tip: In arithmetic sequences, the difference between consecutive terms is always constant, which makes it easy to find patterns or missing terms.

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Math Problem Analysis

Mathematical Concepts

Arithmetic Sequences
Algebra

Formulas

nth term formula of an arithmetic sequence: an = a1 + (n-1) * d

Theorems

Properties of arithmetic sequences

Suitable Grade Level

Grades 8-10