Math Problem Statement

22nd term: –2, –5, –8, –11, –14, ...

Solution

To find the 22nd term in the sequence 2,5,8,11,14,-2, -5, -8, -11, -14, \dots, we first need to determine if it is an arithmetic sequence.

Step 1: Verify if it's an Arithmetic Sequence

An arithmetic sequence has a common difference (dd) between consecutive terms.

Let's calculate the common difference: d=5(2)=5+2=3d = -5 - (-2) = -5 + 2 = -3 d=8(5)=8+5=3d = -8 - (-5) = -8 + 5 = -3 d=11(8)=11+8=3d = -11 - (-8) = -11 + 8 = -3 So, the common difference dd is 3-3.

Step 2: Use the Formula for the nnth Term

The formula for the nnth term of an arithmetic sequence is given by: an=a1+(n1)×da_n = a_1 + (n - 1) \times d Where:

  • ana_n is the nnth term,
  • a1=2a_1 = -2 (the first term),
  • d=3d = -3 (the common difference),
  • n=22n = 22.

Step 3: Calculate the 22nd Term

Substitute the values into the formula: a22=2+(221)×(3)a_{22} = -2 + (22 - 1) \times (-3) a22=2+21×(3)a_{22} = -2 + 21 \times (-3) a22=263a_{22} = -2 - 63 a22=65a_{22} = -65

Final Answer

The 22nd term of the sequence is 65-65.

Would you like more details on this, or have any questions?


Here are five related questions:

  1. What is the sum of the first 22 terms of this sequence?
  2. How would the sequence change if the common difference was 4-4 instead of 3-3?
  3. Can you derive the formula for the nnth term of this arithmetic sequence?
  4. What is the 50th term of the sequence?
  5. How many terms are needed for the sequence to reach 100-100?

Tip: Always double-check your common difference when working with arithmetic sequences.

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Math Problem Analysis

Mathematical Concepts

Arithmetic Sequences

Formulas

Formula for the nth term of an arithmetic sequence

Theorems

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Suitable Grade Level

Grades 7-9