Math Problem Statement

For the sequence an=(-1)n17n2, its first term is    ; its second term is    ; its third term is    ; its fourth term is    ; its 100th term is    .

Solution

The sequence an=(1)n17n2a_n = (-1)^n 17n^2 can be computed term by term using the given formula:

  1. First term (n=1n = 1): a1=(1)11712=17a_1 = (-1)^1 \cdot 17 \cdot 1^2 = -17

  2. Second term (n=2n = 2): a2=(1)21722=1174=68a_2 = (-1)^2 \cdot 17 \cdot 2^2 = 1 \cdot 17 \cdot 4 = 68

  3. Third term (n=3n = 3): a3=(1)31732=1179=153a_3 = (-1)^3 \cdot 17 \cdot 3^2 = -1 \cdot 17 \cdot 9 = -153

  4. Fourth term (n=4n = 4): a4=(1)41742=11716=272a_4 = (-1)^4 \cdot 17 \cdot 4^2 = 1 \cdot 17 \cdot 16 = 272

  5. 100th term (n=100n = 100): a100=(1)100171002=11710000=170000a_{100} = (-1)^{100} \cdot 17 \cdot 100^2 = 1 \cdot 17 \cdot 10000 = 170000

Final Results:

  • First term: 17-17
  • Second term: 6868
  • Third term: 153-153
  • Fourth term: 272272
  • 100th term: 170000170000

Would you like a detailed explanation of the alternating sign behavior or the calculations? Here are some follow-up questions:

  1. How does the term (1)n(-1)^n affect the sequence behavior?
  2. What happens to the sequence as nn becomes very large?
  3. How could you generalize the absolute growth of this sequence?
  4. What is the sum of the first four terms of the sequence?
  5. How would the sequence change if n3n^3 replaced n2n^2?

Tip: The term (1)n(-1)^n is responsible for alternating the sign of the sequence. Odd values of nn produce negative terms, while even values produce positive terms.

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Math Problem Analysis

Mathematical Concepts

Sequences and Series
Alternating Sequences
Exponents
Multiplication

Formulas

an = (-1)^n 17n^2

Theorems

Properties of Exponents
Behavior of Alternating Sequences

Suitable Grade Level

Grades 9-11