Math Problem Statement

the first three terms of an arithmetic sequence are (k+2) , (2k+3) and (4k-2) respectively. Find the value of the constant k

Solution

To solve for the constant kk, we start by using the property of an arithmetic sequence: the difference between consecutive terms is constant.

Given the first three terms of the arithmetic sequence are:

  1. a1=k+2a_1 = k + 2
  2. a2=2k+3a_2 = 2k + 3
  3. a3=4k2a_3 = 4k - 2

The common difference dd of an arithmetic sequence can be found as:

d=a2a1=a3a2d = a_2 - a_1 = a_3 - a_2

Let's compute each difference:

  1. Difference between the second and first terms: a2a1=(2k+3)(k+2)=2k+3k2=k+1a_2 - a_1 = (2k + 3) - (k + 2) = 2k + 3 - k - 2 = k + 1

  2. Difference between the third and second terms: a3a2=(4k2)(2k+3)=4k22k3=2k5a_3 - a_2 = (4k - 2) - (2k + 3) = 4k - 2 - 2k - 3 = 2k - 5

Since these differences are equal, we set them equal to each other:

k+1=2k5k + 1 = 2k - 5

Now, solve for kk:

k+1=2k5k + 1 = 2k - 5

Subtract kk from both sides:

1=k51 = k - 5

Add 5 to both sides:

k=6k = 6

Conclusion

The value of the constant kk is 6.

Would you like more details or have any questions?

Here are 5 related questions for further exploration:

  1. What are the first five terms of this arithmetic sequence with k=6k = 6?
  2. How do you find the nth term of an arithmetic sequence?
  3. Can you derive a formula for the sum of the first n terms of an arithmetic sequence?
  4. What changes in the arithmetic sequence if kk were a different value?
  5. How can we find the common difference if we only know two non-consecutive terms of the sequence?

Tip: Remember, in arithmetic sequences, knowing any two consecutive terms allows you to find the common difference!

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Math Problem Analysis

Mathematical Concepts

Arithmetic Sequence
Algebra

Formulas

Common difference formula: d = a_2 - a_1 = a_3 - a_2
Basic algebraic solving techniques

Theorems

Arithmetic Sequence Properties

Suitable Grade Level

Grades 9-10